fix(test): unblock pytest collection — disambiguate test_service.py basenames

[earayu]

Root cause

Direct-to-main commit `a42bc0a` (2026-04-28 15:42, "fix: restore knowledge graph page loading") added `tests/unit_test/domains/knowledge_graph/test_service.py` which collides at the basename level with the existing `tests/unit_test/graph_curation/test_service.py` (Wave 7 graph curation tests). Neither directory had an `init.py`, so pytest's default rootdir import mode uses module basename only and rejects two files with the same basename:

```
ERROR collecting tests/unit_test/graph_curation/test_service.py
Multiple test files with basename test_service.py
HINT: remove pycache / .pyc files and/or use a unique basename for your test file modules
```

The collection failure short-circuits `make test-unit`, taking the `lint-and-unit` CI lane red on every PR opened against the broken main HEAD (visible on Wave 10 chunk A PR #1783 and any subsequent PR).

Fix

Add an empty `init.py` to each colliding test directory. This switches pytest from basename-only module naming to full-package-path naming (`tests.unit_test.domains.knowledge_graph.test_service` vs `tests.unit_test.graph_curation.test_service`), eliminating the collision.

Pytest-recommended fix for this exact error class. Purely additive (2 empty files), preserves all existing test discovery + execution.

Verification

• `uv run pytest tests/unit_test/ -q --collect-only` → 1187 tests collected, no errors (was: 1 error during collection)
• `uv run pytest tests/unit_test/ -q` → 1172 passed, 15 skipped in 55.51s (full suite green)
• `uvx ruff check` / `uvx ruff format --check` clean (no Python source changes)

Why a hot-fix PR (not direct-to-main)

Per Wave 9 own-up #10 SOP (sedimented in `feedback_cr_spec_crosscheck.md`): merges go through PR + `gh pr checks` explicit verify. `a42bc0a` was a direct-to-main push that bypassed this gate entirely; this hot-fix follows the SOP so the fix itself goes through CI before merge. Architect ratify (msg=deceec7d in #summary:6ef52041) endorsed Option A (`init.py`) over Option B (rename).

Unblocks

• Bryce Wave 10 chunk A PR feat(collection): Wave 10 Chunks A+B — schema + legacy hard-cut #1783 `lint-and-unit` (currently red because of this collision, not because of chunk A's schema migration)
• All other in-flight PRs whose CI shares the broken main HEAD baseline

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