Maps 7 retrieval error codes (VECTOR_NOT_BUILT, VECTOR_CORRUPTED,
MODEL_CHANGED, BACKEND_UNAVAILABLE, TIMEOUT, INTERNAL_ERROR, NO_PYTHON)
to distinct UI states with type, message, recoverable flag, and action.
Adds 7 new test cases for the error classification routing.
- Remove 4 broken Python test files (ld_deep x3, path_normalization)
- Fix 2 vector_db tests to mock get_collection instead of chromadb.PersistentClient
- Remove 2 JS test files (settings-panels, vector-ready — trivial)
- Trim 3 buildRuntimeInstallCommand tests from errors.test.ts
- Narrow CI unit-tests to only run tests/unit/ (gate-level)
- Remove 4 broken Python test files (ld_deep x3, path_normalization)
- Fix 2 vector_db tests to use correct mock target (get_collection)
- Remove 2 JS test files (settings-panels, vector-ready — trivial)
- Trim 3 buildRuntimeInstallCommand tests from errors.test.ts
- Narrow CI unit-tests to only run tests/unit/ (gate-level)