test(graph): expand TS/JS extraction regression fixtures

[abhinav-phi]

What

Expand graph extraction regression coverage for the existing supported languages by adding focused fixtures and semantic regression tests.

Added fixtures:

• src/graph/__tests__/fixtures/typescript-edge-cases.ts
• src/graph/__tests__/fixtures/javascript-edge-cases.js
• src/graph/__tests__/fixtures/tsx-component.tsx
• src/graph/__tests__/fixtures/jsx-component.jsx

Added regression test:

• src/graph/__tests__/extraction-regression.test.ts

The new tests validate:

• Language detection
• Representative node shapes
• Qualified names
• Containment relationships
• Imports
• Calls
• Safe degradation for malformed/ambiguous syntax

No production graph extraction logic was modified.

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Why

Closes #97

This improves regression coverage for the four languages already supported by the code graph preview (TypeScript, JavaScript, TSX, and JSX) while keeping the graph contracts unchanged.

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Type of change

• Bug fix
• New feature
• Refactor
• Docs
• CI/Tooling

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How to test

1. Install dependencies.

npm ci

2. Run type checking.

npm run typecheck

3. Run the focused regression test.

npx vitest src/graph/__tests__/extraction-regression.test.ts --run

Expected result:

• All 14 regression tests pass successfully.

4. Build the project.

npm run build

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Checklist

• Relevant regression tests pass locally (npx vitest src/graph/__tests__/extraction-regression.test.ts --run)
• No breaking changes
• Tested locally with a real project

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Code-graph preview

• This PR targets code-graph-preview, not main
• The linked issue states Target branch: code-graph-preview
• The change follows the frozen LanguageExtractor / FrameworkResolver interfaces
• A focused fixture and semantic assertions for the expected node/edge shape are included
• Any new grammar WASM, extension mapping, extractor, or resolver is registered
• No graph identity, reconciliation, schema, or drift-semantics changes are included

[Yashasvi2229]

Thanks @abhinav-phi, looks good. Merging into code-graph-preview 👍

[theDakshJaitly]

Thank you for the contribution @abhinav-phi
we recently made a discord server for the repo, feel free to join: discord link