Replace TreeSitterParser stubs with real tree-sitter C bindings for
Python, C++, and Elisp parsing. Add tree-sitter core via vcpkg and
language grammars via FetchContent. Implement CST-to-AST converters
with auto-annotation, memory pattern detection, error recovery, and
ParseResult/ParseDiagnostic types. All 34 tests pass (6+7+6+8+7).
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
