test(api): cover frontend-required routes (#84)

[hardikuppal04]

Summary

• add ASGI integration coverage for the frontend-required API routes
• cover the previously missing architecture, engineering-review, owner-delete, AI-config, and AI-connection happy paths
• verify standard ErrorResponse envelopes and request correlation on representative failures
• ensure generic 500 responses do not leak exception or traceback text

Why

The frontend depends on these routes across authentication, repositories, analysis, documentation, exports, and AI settings. This gives each route a real success path and an error contract check without changing runtime behavior.

Validation

• python -m pytest --basetemp ..\\.pytest-tmp-84-audit-focused ...: 106 passed, 1 skipped
• python -m pytest --ignore=tests/benchmark --basetemp ..\\.pytest-tmp-84-audit-nonbenchmark: 323 passed, 4 skipped
• python -m pip check: no broken requirements

The complete local suite has two unrelated benchmark assertions on Windows because a fixture checked in as LF is materialized as CRLF (97 bytes instead of the manifest's 96). No benchmark files are part of this PR.

Closes #84

[SHAURYAKSHARMA24]

Thanks for the work on this, Hardik. The overall approach is solid and the added route coverage is useful, but I found two issues that need addressing before approval:

1. Make assert_error_response enforce the exact response contract.
   ErrorResponse.model_validate() currently accepts missing optional fields and silently ignores unexpected fields. This means a response missing details, or even containing an unexpected field such as traceback, can pass. Please require exactly code, message, details, and request_id, and add focused tests for missing fields, unexpected fields, and mismatched request IDs.

2. Add a failure-path contract test for POST /auth/logout.
   The current logout test only covers successful/idempotent 204 responses. Issue #84 requires both a happy path and a failure path for each frontend-required route. Please add a deterministic ASGI integration test for a documented logout failure (429 or 500) and validate it with the strict shared error helper. If testing 500, also confirm no exception or traceback information is exposed.

Please keep the changes narrowly scoped, reuse the existing fixtures, and include the relevant focused and non-benchmark backend test results when ready for re-review.