Simplify Documentation Stack: Remove mkdocstrings and gen-files

[Kilo59]

As the project evolves, we should simplify our documentation stack to remove the maintenance burden of auto-generated API docs and prepare for a future Zensical migration. ruff-sync is a CLI tool, and the auto-generated API reference (gen-files + mkdocstrings) is low value compared to hand-authored documentation that focuses on the CLI interface and core integration points.

Tasks

1. Remove Dependencies
   Remove mkdocstrings and mkdocs-gen-files from pyproject.toml under [dependency-groups.docs].

2. Delete Generation Scripts
   Delete the file docs/gen_ref_pages.py. This script is currently used by gen-files to discover and generate API pages.

3. Update mkdocs.yml Plugins
   Remove the gen-files and mkdocstrings plugins from the plugins: block in mkdocs.yml.

# Remove these:
- gen-files:
    scripts:
      - docs/gen_ref_pages.py
- mkdocstrings:
    handlers:
      python:
        paths: [src]
        # ... (options)

4. Create Hand-Authored API Reference (docs/reference/api.md)
   Create a new file docs/reference/api.md that provides a high-level summary of the ruff-sync CLI and core library. It should include:

• CLI Commands: A summary of pull, check, and init commands (use ruff-sync --help as a guide).
• Core Result Types: A brief overview of the Config (TypedDict) and FetchResult (NamedTuple) from src/ruff_sync/core.py.
• Main Entry Point: Mention that the core logic resides in ruff_sync.core.sync or the cli.main function.

5. Update Navigation
   In mkdocs.yml, update the nav: block so that "API Reference" points directly to the new api.md file:

nav:
  - ...
  - API Reference: reference/api.md

Validation

• Run uv run mkdocs build and ensure the site builds without errors and the new API Reference page is correctly rendered.