Add complete HTTP server and rendering layer for the help catalog:
- render.go: Markdown-to-HTML via goldmark (GFM, typographer, raw HTML)
- server.go: HTTP server with 6 routes (HTML index/topic/search + JSON API)
- templates.go: Embedded HTML templates with dark theme (bg #0d1117)
- templates/: base, index, topic, search, 404 page templates
- generate.go: Static site generator with client-side JS search
- ingest.go: CLI help text parser (Usage/Flags/Examples/Commands sections)
320 tests passing, 95.5% coverage, race-clean, vet-clean.
Co-Authored-By: Virgil <virgil@lethean.io>
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
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