Add Xquik OpenAPI parser fixture

[kriptoburak]

Summary

• add a compact Xquik OpenAPI 3.1 fixture for GET /api/v1/x/tweets/search
• align pagination, response schemas, filter references, and authentication with the current public contract
• assert parser output for method, path, tag, parameters, response type, and security
• parse shared OpenAPI Path Item parameters and preserve operation-level overrides

Independent repository fix

The parser previously read only operation-level parameters. OpenAPI also permits parameters on the Path Item, where they apply to every operation and can be overridden by matching operation parameters. The parser now merges both levels by parameter location and name, with regression coverage for inheritance and overrides.

Validation

• pnpm test: 423 passed
• pnpm run typecheck: passed
• pnpm run build: passed
• JSON fixtures and diff whitespace validated
• Xquik fixture checked against the live public OpenAPI document

[kriptoburak]

This remains conflict-free and the focused parser, typecheck, and build validations passed. I can adjust the fixture if you prefer a smaller contract.

[kriptoburak]

I refreshed this PR on the current main branch. The Xquik fixture now matches the live search response and authentication contract. I also fixed the parser to inherit OpenAPI Path Item parameters while preserving operation-level overrides. All 423 tests, type checking, and the production build pass.