feat: replace regex README parser with markdown-it-py AST parser

Introduce parse_readme() which uses MarkdownIt to build a full AST
instead of line-by-line regex matching. The function splits the document
at the thematic break, groups nodes by h2 heading, extracts category
descriptions from leading italic paragraphs, and separates the
Categories, Resources, and Contributing sections cleanly.

Add markdown-it-py==4.0.0 (+ mdurl) as a runtime dependency to support
the new parser.

Tests cover section counts, names, slugs, descriptions, content
presence, boundary conditions (no separator, no description), and mixed
description markup.

Co-Authored-By: Claude <noreply@anthropic.com>

website/tests/test_readme_parser.py

@@ -2,9 +2,10 @@
 
 import os
 import sys
+import textwrap
 
 sys.path.insert(0, os.path.join(os.path.dirname(__file__), ".."))
-from readme_parser import render_inline_html, render_inline_text
+from readme_parser import parse_readme, render_inline_html, render_inline_text
 
 from markdown_it import MarkdownIt
 from markdown_it.tree import SyntaxTreeNode
@@ -67,3 +68,135 @@ class TestRenderInlineText:
     def test_code_inline_kept(self):
         children = _parse_inline("`code` here")
         assert render_inline_text(children) == "code here"
+
+
+MINIMAL_README = textwrap.dedent("""\
+    # Awesome Python
+
+    Some intro text.
+
+    ---
+
+    ## Alpha
+
+    _Libraries for alpha stuff._
+
+    - [lib-a](https://example.com/a) - Does A.
+    - [lib-b](https://example.com/b) - Does B.
+
+    ## Beta
+
+    _Tools for beta._
+
+    - [lib-c](https://example.com/c) - Does C.
+
+    # Resources
+
+    Where to discover resources.
+
+    ## Newsletters
+
+    - [News One](https://example.com/n1)
+    - [News Two](https://example.com/n2)
+
+    ## Podcasts
+
+    - [Pod One](https://example.com/p1)
+
+    # Contributing
+
+    Please contribute!
+""")
+
+
+class TestParseReadmeSections:
+    def test_category_count(self):
+        cats, resources = parse_readme(MINIMAL_README)
+        assert len(cats) == 2
+
+    def test_resource_count(self):
+        cats, resources = parse_readme(MINIMAL_README)
+        assert len(resources) == 2
+
+    def test_category_names(self):
+        cats, _ = parse_readme(MINIMAL_README)
+        assert cats[0]["name"] == "Alpha"
+        assert cats[1]["name"] == "Beta"
+
+    def test_category_slugs(self):
+        cats, _ = parse_readme(MINIMAL_README)
+        assert cats[0]["slug"] == "alpha"
+        assert cats[1]["slug"] == "beta"
+
+    def test_category_description(self):
+        cats, _ = parse_readme(MINIMAL_README)
+        assert cats[0]["description"] == "Libraries for alpha stuff."
+        assert cats[1]["description"] == "Tools for beta."
+
+    def test_category_content_has_entries(self):
+        cats, _ = parse_readme(MINIMAL_README)
+        assert "lib-a" in cats[0]["content"]
+        assert "lib-b" in cats[0]["content"]
+
+    def test_resource_names(self):
+        _, resources = parse_readme(MINIMAL_README)
+        assert resources[0]["name"] == "Newsletters"
+        assert resources[1]["name"] == "Podcasts"
+
+    def test_resource_content(self):
+        _, resources = parse_readme(MINIMAL_README)
+        assert "News One" in resources[0]["content"]
+        assert "Pod One" in resources[1]["content"]
+
+    def test_contributing_skipped(self):
+        cats, resources = parse_readme(MINIMAL_README)
+        all_names = [c["name"] for c in cats] + [r["name"] for r in resources]
+        assert "Contributing" not in all_names
+
+    def test_no_separator(self):
+        cats, resources = parse_readme("# Just a heading\n\nSome text.\n")
+        assert cats == []
+        assert resources == []
+
+    def test_no_description(self):
+        readme = textwrap.dedent("""\
+            # Title
+
+            ---
+
+            ## NullDesc
+
+            - [item](https://x.com) - Thing.
+
+            # Resources
+
+            ## Tips
+
+            - [tip](https://x.com)
+
+            # Contributing
+
+            Done.
+        """)
+        cats, resources = parse_readme(readme)
+        assert cats[0]["description"] == ""
+        assert "item" in cats[0]["content"]
+
+    def test_description_with_link_stripped(self):
+        readme = textwrap.dedent("""\
+            # T
+
+            ---
+
+            ## Algos
+
+            _Algorithms. Also see [awesome-algos](https://example.com)._
+
+            - [lib](https://x.com) - Lib.
+
+            # Contributing
+
+            Done.
+        """)
+        cats, _ = parse_readme(readme)
+        assert cats[0]["description"] == "Algorithms. Also see awesome-algos."