fix(extractor): attribute file-scope calls to synthetic <file> caller (TS/JS, Python)

[lalith0407]

Summary

Fixes #721 · Refs #367 · Follows the convention introduced in #400 (PHP)

extractCallGraph() in the TypeScript/JavaScript and Python extractors only recorded a call when functionStack.length > 0. Any call outside a named function was silently dropped: module-level wiring (app.use(router), app = Flask(__name__)), if __name__ == "__main__": blocks, top-level main() invocations, IIFEs, and anonymous callbacks at file scope (items.forEach(x => register(x))). Entry-point, bootstrap, and config modules therefore ended up with an empty or near-empty call graph.

Changes

• <file> caller convention. When no enclosing named function exists, the call is now attributed to the synthetic caller "<file>", the same stable, language-neutral identifier fix(php-extractor): capture file-scope calls + map include/require as imports (#367) #400 uses for PHP. Calls inside named functions are unchanged.
• FILE_SCOPE_CALLER constant. Added export const FILE_SCOPE_CALLER = "<file>" in plugins/extractors/types.ts and re-exported it from @understand-anything/core, so every extractor (and fix(php-extractor): capture file-scope calls + map include/require as imports (#367) #400's PHP fix, once merged) can share one definition instead of repeating the string.
• Mapping <file> to the file node. Edges are built by the file-analyzer agent rather than a code-level merge step, so I added a note to agents/file-analyzer.md: a caller of "<file>" means file-scope code; never create a function node named <file>, use the file node (file:<path>) as the edge source.
  Question for maintainers: would you prefer this enforced in code instead (e.g. rewriting <file> callers to the file node id in extract-structure-result.mjs / the merge script) rather than relying on the prompt? Happy to add that in this PR or a follow-up.

Tests

• TypeScript (5 new): top-level main(); express() / app.use(router) at module scope; calls inside a top-level IIFE; anonymous items.forEach callback; a regression test that calls inside a named function (including nested anonymous callbacks) stay attributed to that function with no <file> entries.
• Python (4 new): top-level main(); calls under an if __name__ == "__main__": guard; module-level Flask(...) / app.register_blueprint(...); a regression test that a file whose calls are all inside functions emits no <file> entries.
• Updated: the Python test ignores top-level calls (no caller) encoded the old dropping behaviour. It's renamed to attributes top-level calls to the synthetic <file> caller and now expects two <file> entries (print, main).

Test results (Node 22.23.3, pnpm 10)

• pnpm --filter @understand-anything/core build: ✅
• pnpm --filter @understand-anything/core test: ✅ 47 files, 1022 tests passed
• pnpm test: ✅ 38 files passed, 1 skipped; 786 tests passed, 12 skipped (the skips are pre-existing)
• pnpm lint: ✅ clean

Notes

• Scope is deliberately limited to TS/JS and Python. The same functionStack.length > 0 check exists in the Go, Rust, Java, C#, C++, Kotlin, Ruby, Scala and Dart extractors; I can follow up per language.
• fix(extractor): capture static CommonJS imports and exports #715 also touches typescript-extractor.ts, so there may be a trivial conflict.