Add TreeSitter integration for language-aware features

[tyzerrr]

Summary

Use TreeSitter for per-language function detection and AST-aware code analysis.

Context

The 99 plugin has per-language modules with TreeSitter queries for function extraction, import detection, and call analysis.

Acceptance Criteria

• Language module interface
• TreeSitter queries for common languages (Lua, TypeScript, Go)
• Function body detection for smarter context selection