MCP T16 — Add 5 new tree-sitter languages (Go, Rust, TypeScript, Ruby, C++) + re-enable C

[DvirDukhan]

Context

After T15 extracts a TreeSitterAnalyzer base class, adding new languages becomes a small subclass per language. This ticket adds 5 new languages (Go, Rust, TypeScript, Ruby, C++) and re-enables C (currently commented out at api/analyzers/source_analyzer.py:28). With this change the indexer covers 11 languages total: Python, JavaScript, TypeScript, Java, C#, Kotlin, Go, Rust, Ruby, C, C++.

This dramatically widens the set of repos cgraph (and the new MCP server) can usefully index.

Scope (in)

Six small subclasses of TreeSitterAnalyzer:

1. Go — api/analyzers/go/analyzer.py, deps tree-sitter-go, extension .go
2. Rust — api/analyzers/rust/analyzer.py, deps tree-sitter-rust, extension .rs
3. TypeScript — api/analyzers/typescript/analyzer.py, deps tree-sitter-typescript, extensions .ts and .tsx
4. Ruby — api/analyzers/ruby/analyzer.py, deps tree-sitter-ruby, extension .rb
5. C++ — api/analyzers/cpp/analyzer.py, deps tree-sitter-cpp, extensions .cc, .cpp, .cxx, .hpp, .hh
6. C (re-enable) — uncomment and fix any rot in api/analyzers/c/analyzer.py; ensure it uses the new base class from T15

Each subclass:

• Declares its tree-sitter Language instance, node-type-to-label map, query templates, and file extensions.
• Registers itself in api/analyzers/source_analyzer.py's extension dispatch dict.

Per-language test fixtures in tests/analyzers/fixtures/<lang>/ with a small known call graph and assertion contract (similar to T3 but per language).

Scope (out)

• Replacing the LSP-based Java/C# analyzers with tree-sitter (these stay on multilspy).
• Languages beyond the 6 listed (Swift, PHP, Scala, etc. — Phase 2).
• Cross-language call resolution (e.g. JS calling a TS function).

Files

• new api/analyzers/go/analyzer.py
• new api/analyzers/rust/analyzer.py
• new api/analyzers/typescript/analyzer.py
• new api/analyzers/ruby/analyzer.py
• new api/analyzers/cpp/analyzer.py
• modified api/analyzers/c/analyzer.py (re-enable, port to base class)
• modified api/analyzers/source_analyzer.py (register new extensions; uncomment C)
• modified pyproject.toml (add tree-sitter-go, tree-sitter-rust, tree-sitter-typescript, tree-sitter-ruby, tree-sitter-cpp; check existing tree-sitter-c version)
• new tests/analyzers/fixtures/go/, rust/, typescript/, ruby/, cpp/, c/
• new tests/analyzers/test_new_languages.py
• modified README.md (Supported languages section)

Acceptance criteria

• Indexing a multi-language fixture covering all 6 new/re-enabled languages produces nodes for each.
• Per-language test asserts a known call chain in each fixture is correctly captured (entry point → at least one downstream function).
• All 11 languages appear in source_analyzer.py's extension dispatch.
• README "Supported languages" section updated to list 11 languages.
• make lint and make test clean.
• Existing tests for Python/JS/Kotlin/Java/C# pass unchanged.
• pyproject.toml declares all new tree-sitter grammar deps with sane version pins.

Dependencies

• MCP T15 — Tree-sitter analyzer base class refactor #663 (T15 — base class refactor) — hard dep; subclasses can't be written without the base.

Notes for the implementer

• Per-language fixtures should be tiny — 3-4 files with a known entrypoint → service → repo call chain is enough. Don't pull in real-world projects.
• Tree-sitter grammar packages are pre-built wheels for most platforms. Verify the CI matrix can install all 5 new ones.
• When re-enabling C, find out why it was commented out — look at git blame on source_analyzer.py:28. If there's a known bug, fix it before re-enabling.
• TypeScript shares much of its grammar with JavaScript. Be careful that .ts files don't get routed to the JS analyzer by accident.