Language guide

Moved. Language support pages are generated on the website from crates/rgctl-lang-*/{id}-ast-coverage.json (see languages/README.md).

Tier-1 deep-analysis languages ship grammar-verified *-ast-coverage.json + single-pass extract_all (ScopeStack + KindDispatchTable + parse_with_pool). That is distinct from the ~60 language/config plugins in languages.toml. Drift gates: RGCTL_AST_COVERAGE_STRICT=1 (build), RGCTL_AST_COVERAGE_TRACK=1 (runtime hit tracking in depth tests).

Contributor checklist: tier-1-language-support.md · language-testing-guide.md · contributor-checklist.md.