Add test catalogue generator (scripts/test_catalogue.py + docs/TEST_CASES.md) #169

Context

Automated test catalogue, follow-up from closed PR #41.

PR #41 proposed scripts/test_catalogue.py — a script that walks the test tree and generates docs/TEST_CASES.md, listing every test case with ID, file and objective, grouped by category. CI then runs scripts/test_catalogue.py --check to keep the doc current (fails CI if the generated doc is out of date relative to the actual tests).

The current state: docs/TEST_CASES.md doesn't exist. Tests are discoverable only by pytest --collect-only, which doesn't give you a per-test objective or a stable ID.

Scope

• scripts/test_catalogue.py reading pytest.ini markers and test files, generating docs/TEST_CASES.md
• The script extracts test IDs from docstrings or from a @pytest.mark.id("...") decorator (decide which during implementation)
• CI check mode (--check) that fails if the committed docs/TEST_CASES.md differs from a fresh generation
• Add the check to the free-tier Quality Gate job

Out of scope

• Backfilling IDs or docstrings on existing tests (that's a separate, larger housekeeping PR)
• Any cross-referencing with VCRM or BR requirements (#A, #B, #C aside, that's its own problem)

Done when

• python scripts/test_catalogue.py --check runs in CI and passes
• docs/TEST_CASES.md exists on main with current test inventory
• A new test added without updating the doc fails CI with a clear "run scripts/test_catalogue.py and commit the result" message

Related

• Group tests into unit, system, SIT, performance, accessibility and UAT #41 (closed, superseded by #A + #B + this)
• #A: Test folder reorganisation (prerequisite — categories need to exist before cataloguing)