Add AST extraction tests, broader ignore patterns, build dist

- ast-extract.ts: Support tree-sitter-python and tree-sitter-go grammar
  loading (pkg.language fallback)
- discover.ts: Add cache directories to default ignore (.cache, tmp,
  temp, .turbo, .parcel-cache, .eslintcache, .prettiercache)
- tests: Add TypeScript AST extraction tests (exports + imports)
- Verified on real project: media_library_viewer (196 .pi-map.md files)
  with accurate React component extraction
- Build: npm run build produces clean dist/ output

All 16 tests pass.

package.json

@@ -35,6 +35,8 @@
   "dependencies": {
     "ignore": "^5.3.0",
     "tree-sitter": "^0.21.0",
+    "tree-sitter-go": "^0.25.0",
+    "tree-sitter-python": "^0.25.0",
     "tree-sitter-typescript": "^0.21.0"
   }
 }