refactor: replace hardcoded colors in sidebar conversation list with tokens

Migrate the Conversations sidebar section to semantic tokens: focus rings to
ring-text-primary (keeps >=3:1 contrast in both modes; the mid-gray ring would
fail WCAG 1.4.11 on dark), the active-conversation indicator and hover-fade
gradient to surface/text tokens, and the pagination controls. Removes every
dark: color twin; no behavior change.

client/src/components/Conversations/Conversations.tsx

@@ -87,7 +87,7 @@ interface ChatsHeaderProps {
 }
 
 const headerIconButtonClassName =
-  'flex h-7 w-7 shrink-0 items-center justify-center rounded-md text-text-secondary outline-none transition-colors hover:bg-surface-active-alt hover:text-text-primary focus-visible:outline-none focus-visible:ring-2 focus-visible:ring-inset focus-visible:ring-black dark:focus-visible:ring-white';
+  'flex h-7 w-7 shrink-0 items-center justify-center rounded-md text-text-secondary outline-none transition-colors hover:bg-surface-active-alt hover:text-text-primary focus-visible:outline-none focus-visible:ring-2 focus-visible:ring-inset focus-visible:ring-text-primary';
 
 /** Collapsible header for the Chats section */
 const ChatsHeader: FC<ChatsHeaderProps> = memo(({ isExpanded, onToggle }) => {
@@ -106,7 +106,7 @@ const ChatsHeader: FC<ChatsHeaderProps> = memo(({ isExpanded, onToggle }) => {
     <div className="flex h-8 w-full items-center gap-0.5 pr-2">
       <button
         onClick={onToggle}
-        className="group flex min-w-0 flex-1 items-center gap-1 rounded-lg px-1 py-2 text-xs font-bold text-text-secondary outline-none focus-visible:outline-none focus-visible:ring-2 focus-visible:ring-inset focus-visible:ring-black dark:focus-visible:ring-white"
+        className="group flex min-w-0 flex-1 items-center gap-1 rounded-lg px-1 py-2 text-xs font-bold text-text-secondary outline-none focus-visible:outline-none focus-visible:ring-2 focus-visible:ring-inset focus-visible:ring-text-primary"
         type="button"
         aria-expanded={isExpanded}
       >

client/src/components/Conversations/Convo.tsx

@@ -218,9 +218,9 @@ function Conversation({
     <div
       ref={containerRef}
       className={cn(
-        'group relative flex h-12 w-full items-center rounded-lg outline-none focus-visible:outline-none focus-visible:ring-2 focus-visible:ring-inset focus-visible:ring-black dark:focus-visible:ring-white md:h-9',
+        'group relative flex h-12 w-full items-center rounded-lg outline-none focus-visible:outline-none focus-visible:ring-2 focus-visible:ring-inset focus-visible:ring-text-primary md:h-9',
         isActiveConvo || isPopoverActive
-          ? 'bg-surface-active-alt before:absolute before:bottom-1 before:left-0 before:top-1 before:w-0.5 before:rounded-full before:bg-black dark:before:bg-white'
+          ? 'bg-surface-active-alt before:absolute before:bottom-1 before:left-0 before:top-1 before:w-0.5 before:rounded-full before:bg-text-primary'
           : 'hover:bg-surface-active-alt',
       )}
       role="button"

client/src/components/Conversations/HoverToggle.tsx

@@ -23,12 +23,12 @@ const HoverToggle = ({
       <div
         onClick={onClick}
         className={cn(
-          'peer items-center gap-1.5 rounded-r-lg from-gray-900 pl-2 pr-2 dark:text-white',
+          'peer items-center gap-1.5 rounded-r-lg pl-2 pr-2 text-text-primary',
           isPopoverActive || isActiveConvo ? 'flex' : 'hidden group-hover:flex',
           isActiveConvo
-            ? 'from-gray-50 from-85% to-transparent group-hover:bg-gradient-to-l group-hover:from-gray-200 dark:from-gray-800 dark:group-hover:from-gray-800'
-            : 'z-50 from-gray-50 from-0% to-transparent hover:bg-gradient-to-l hover:from-gray-200 dark:from-gray-800 dark:hover:from-gray-800',
-          isPopoverActive && !isActiveConvo ? 'from-gray-50 dark:from-gray-800' : '',
+            ? 'from-surface-secondary from-85% to-transparent group-hover:bg-gradient-to-l group-hover:from-surface-active-alt'
+            : 'z-50 from-surface-secondary from-0% to-transparent hover:bg-gradient-to-l hover:from-surface-active-alt',
+          isPopoverActive && !isActiveConvo ? 'from-surface-secondary' : '',
           className,
         )}
       >

client/src/components/Conversations/Pages.tsx

@@ -30,20 +30,20 @@ export default function Pages({
       <button
         onClick={clickHandler(previousPage)}
         className={
-          'btn btn-small bg-transition m-auto flex gap-2 transition hover:bg-gray-800 disabled:text-gray-300 dark:text-white dark:disabled:text-gray-400' +
+          'btn btn-small bg-transition m-auto flex gap-2 text-text-primary transition hover:bg-surface-hover disabled:text-text-tertiary' +
           (pageNumber <= 1 ? ' hidden-visibility' : '')
         }
         disabled={pageNumber <= 1}
       >
         &lt;
       </button>
-      <span className="flex-none text-gray-400">
+      <span className="flex-none text-text-tertiary">
         {pageNumber} / {pages}
       </span>
       <button
         onClick={clickHandler(nextPage)}
         className={
-          'btn btn-small bg-transition m-auto flex gap-2 transition hover:bg-gray-800 disabled:text-gray-300 dark:text-white dark:disabled:text-gray-400' +
+          'btn btn-small bg-transition m-auto flex gap-2 text-text-primary transition hover:bg-surface-hover disabled:text-text-tertiary' +
           (pageNumber >= pages ? ' hidden-visibility' : '')
         }
         disabled={pageNumber >= pages}

client/src/components/Conversations/ProjectsSection.tsx

@@ -47,7 +47,7 @@ import store from '~/store';
 const INLINE_CHAT_LIMIT = 8;
 
 const iconButtonClassName =
-  'flex h-7 w-7 shrink-0 items-center justify-center rounded-md text-text-secondary outline-none transition-colors hover:bg-surface-active-alt hover:text-text-primary focus-visible:outline-none focus-visible:ring-2 focus-visible:ring-inset focus-visible:ring-black dark:focus-visible:ring-white';
+  'flex h-7 w-7 shrink-0 items-center justify-center rounded-md text-text-secondary outline-none transition-colors hover:bg-surface-active-alt hover:text-text-primary focus-visible:outline-none focus-visible:ring-2 focus-visible:ring-inset focus-visible:ring-text-primary';
 
 function ProjectRenameDialog({
   open,
@@ -250,7 +250,7 @@ const ProjectChatsInline = memo(function ProjectChatsInline({
         <button
           type="button"
           onClick={onShowAll}
-          className="ml-1 mt-0.5 rounded-md px-2 py-1 text-xs font-medium text-text-secondary outline-none transition-colors hover:text-text-primary focus-visible:outline-none focus-visible:ring-2 focus-visible:ring-inset focus-visible:ring-black dark:focus-visible:ring-white"
+          className="ml-1 mt-0.5 rounded-md px-2 py-1 text-xs font-medium text-text-secondary outline-none transition-colors hover:text-text-primary focus-visible:outline-none focus-visible:ring-2 focus-visible:ring-inset focus-visible:ring-text-primary"
         >
           {localize('com_ui_show_all')}
         </button>
@@ -332,7 +332,7 @@ const ProjectItem = memo(
             onClick={() => setExpanded((prev) => !prev)}
             aria-expanded={expanded}
             aria-label={project.name}
-            className="flex min-w-0 flex-1 items-center gap-1.5 rounded-lg py-1.5 pl-1.5 pr-14 text-left outline-none focus-visible:ring-2 focus-visible:ring-inset focus-visible:ring-black dark:focus-visible:ring-white"
+            className="flex min-w-0 flex-1 items-center gap-1.5 rounded-lg py-1.5 pl-1.5 pr-14 text-left outline-none focus-visible:ring-2 focus-visible:ring-inset focus-visible:ring-text-primary"
           >
             <ChevronRight
               className={cn(
@@ -456,7 +456,7 @@ const ProjectsSection = ({ toggleNav, isAuthenticated }: ProjectsSectionProps) =
         <button
           type="button"
           onClick={() => setIsCreateOpen(true)}
-          className="flex w-full items-center gap-2 rounded-lg px-2 py-1.5 text-sm text-text-secondary outline-none transition-colors hover:bg-surface-hover hover:text-text-primary focus-visible:outline-none focus-visible:ring-2 focus-visible:ring-inset focus-visible:ring-black dark:focus-visible:ring-white"
+          className="flex w-full items-center gap-2 rounded-lg px-2 py-1.5 text-sm text-text-secondary outline-none transition-colors hover:bg-surface-hover hover:text-text-primary focus-visible:outline-none focus-visible:ring-2 focus-visible:ring-inset focus-visible:ring-text-primary"
         >
           <FolderPlus className="h-4 w-4 shrink-0" aria-hidden="true" />
           <span className="truncate">{localize('com_ui_new_project')}</span>
@@ -479,7 +479,7 @@ const ProjectsSection = ({ toggleNav, isAuthenticated }: ProjectsSectionProps) =
             <button
               type="button"
               onClick={openProjects}
-              className="flex w-full items-center gap-2 rounded-lg px-2 py-1.5 text-xs font-medium text-text-secondary outline-none transition-colors hover:bg-surface-hover hover:text-text-primary focus-visible:outline-none focus-visible:ring-2 focus-visible:ring-inset focus-visible:ring-black dark:focus-visible:ring-white"
+              className="flex w-full items-center gap-2 rounded-lg px-2 py-1.5 text-xs font-medium text-text-secondary outline-none transition-colors hover:bg-surface-hover hover:text-text-primary focus-visible:outline-none focus-visible:ring-2 focus-visible:ring-inset focus-visible:ring-text-primary"
             >
               {localize('com_ui_all_projects')}
             </button>
@@ -501,7 +501,7 @@ const ProjectsSection = ({ toggleNav, isAuthenticated }: ProjectsSectionProps) =
             setStoredExpanded(!isExpanded);
             setHasToggledSection(true);
           }}
-          className="group flex min-w-0 flex-1 items-center gap-1 rounded-lg px-1 py-2 text-xs font-bold text-text-secondary outline-none focus-visible:outline-none focus-visible:ring-2 focus-visible:ring-inset focus-visible:ring-black dark:focus-visible:ring-white"
+          className="group flex min-w-0 flex-1 items-center gap-1 rounded-lg px-1 py-2 text-xs font-bold text-text-secondary outline-none focus-visible:outline-none focus-visible:ring-2 focus-visible:ring-inset focus-visible:ring-text-primary"
           type="button"
           aria-expanded={isExpanded}
         >