Replaces the activation-zone approach with an explicit opt-in setting
in Settings -> Other ("Allow docking remote toolbar to any window
edge"). This addresses the concern that a low-intent horizontal drag
shouldn't be able to trigger a high-impact orientation change, while
still letting users who want multi-edge docking opt in cleanly.
Default (toggle off):
- The original horizontal slide is preserved.
- The bug fix from the first commit still applies: dragging the
handle moves the whole toolbar, and the position persists across
collapse/expand (no more re-center on re-open).
- Draggable is axis-locked to horizontal so the feedback widget
stays on the top line during drag.
Opt-in (toggle on):
- Full nearest-edge wins with the live preview ghost and corner
hysteresis; toolbar reflows vertically on left/right docks.
- Draggable is unlocked for 2D drag.
Reads the option via mainGetLocalBoolOptionSync so the toolbar's
default state matches what the settings checkbox shows; the option
key uses the allow- prefix so unset defaults to off.
Takes effect on next session (setting is read at session init).
The setting key (allow-multi-edge-toolbar-dock) is read by the
existing local-options machinery and persists per-install without
needing to be registered in libs/hbb_common's KEYS_LOCAL_SETTINGS.
Can add that registration in a parallel hbb_common PR if preferred.
c403cd8440