[Kinflou]

Moves feature support out of Reference → Tools (next to the CLI) into a per-language specification.

• Reference → Languages → Overview explains the four states and how conformance proves them, then shows the code generators side by side.
• Reference → Languages → Rust / TypeScript each have:
  • Code generation: every feature with what it covers, the state and note, the tracking issue, and the fixtures that prove it;
  • Runtime: a placeholder until runtime conformance covers the language. That work is next, in the runtime repo, followed by comline-typescript.
• scripts/sync-language-support.py renders all three from generation's features.json (structured, not the Markdown table). A generator with no page is an error that names the page to add. It replaces sync-generator-support.py, and the drift workflow is renamed to language-support-drift.yml.
• The validator guide and the CLI reference link to the new pages.

The strict build is clean, --check passes against generation's features.json, and check-cli-drift.py passes.