docs(feat[autodoc]): Add sphinx-autodoc-docutils, sphinx-autodoc-sphinx, and package-reference directive

why: Enable auto-generated reference tables for directives, roles, and
config values across all package docs pages, replacing static Markdown
tables with live introspection.
what:
- Add sphinx-autodoc-docutils package with autodirective, autorole,
  autodirective-index, autorole-index directives
- Add sphinx-autodoc-sphinx package with autoconfigvalue,
  autoconfigvalues, autoconfigvalue-index directives
- Add package_reference.py docs extension (auto-generates registered
  surface tables from setup() introspection)
- Rewrite all package docs pages to use live autodoc directives
- Add argparse_neo_demo.py with subcommand and epilog examples
- Register new extensions in conf.py with env-gated intersphinx
- Add workspace packages to pyproject.toml, ruff, and mypy config
- Add tests for autodoc-docutils, autodoc-sphinx, and package-reference
- Add CSS for package demo cards and font specimens
- Add redirects for new package doc pages

Author: tony

docs/_ext/argparse_neo_demo.py

@@ -0,0 +1,64 @@
+"""Demo parser factories for the sphinx-argparse-neo docs page."""
+
+from __future__ import annotations
+
+import argparse
+import textwrap
+
+
+def build_parser() -> argparse.ArgumentParser:
+    """Return a parser with groups, subcommands, and example epilogs."""
+    parser = argparse.ArgumentParser(
+        prog="gp-demo",
+        description="Inspect and synchronize documentation metadata.",
+    )
+    parser.add_argument(
+        "--format",
+        choices=["table", "json"],
+        default="table",
+        help="output format",
+    )
+    parser.add_argument(
+        "--jobs",
+        type=int,
+        default=4,
+        help="number of worker jobs",
+    )
+
+    subcommands = parser.add_subparsers(dest="command")
+
+    sync = subcommands.add_parser(
+        "sync",
+        help="synchronize package docs",
+        description="Synchronize package metadata into the docs site.",
+        epilog=textwrap.dedent(
+            """
+            examples:
+                gp-demo sync packages/sphinx-fonts
+                gp-demo sync packages/sphinx-gptheme
+
+            Machine-readable output examples:
+                gp-demo sync --format json packages/sphinx-fonts
+            """
+        ),
+        formatter_class=argparse.RawDescriptionHelpFormatter,
+    )
+    sync.add_argument("target", metavar="PACKAGE", help="package to synchronize")
+    sync.add_argument(
+        "--strict",
+        action="store_true",
+        help="fail on missing docs coverage",
+    )
+
+    doctor = subcommands.add_parser(
+        "doctor",
+        help="check docs build health",
+        description="Run validation checks for the documentation site.",
+    )
+    doctor.add_argument(
+        "--warnings-as-errors",
+        action="store_true",
+        help="treat warnings as fatal",
+    )
+
+    return parser