Add tree-sitter parsing for precise AST extraction

[francomano]

Problem

CoreBall v0.1 uses Python stdlib ast for Python and regex for JS/TS. This limits accuracy and language coverage. The competitive landscape (codegraph, graphsift, codescope) all use tree-sitter for precise, multi-language parsing.

Proposal

Integrate tree-sitter as the primary parser for all supported languages:

• Python, JavaScript, TypeScript (current) - improve precision
• Go, Rust, Java, C#, PHP, Ruby, C, C++, Swift, Kotlin (new)
• Tree-sitter grammars compile to WASM - no native build needed for Python

Benefits

• 20+ languages from one parser backend
• Precise AST extraction (functions, classes, methods, imports, calls)
• Match competitor capabilities (codegraph supports 23 languages)
• WASM grammars keep the zero-dependency promise

Acceptance criteria

• tree-sitter integrated as optional parser backend
• At least 5 new languages supported
• Existing Python/JS/TS parsing preserved as fallback
• Benchmark comparison vs current regex-based extraction