[chore] remove all remaining type:ignore suppressions from tests/

Converts 115 `# type: ignore[...]` suppressions across 23 test files to
no-suppression patterns (helper-return widening to Any, local Any aliases,
cc:Any aliases, cast at narrow call sites, typed fixtures) so the hard
no-type:ignore convention holds across tests/. No test logic or assertions
changed — only mock-wiring mechanics and type annotations.

Gate: ruff check tests/ clean; mypy tests/ (538 files) clean; 176 changed-file
tests pass. Zero real suppressions remain (the 7 grep hits are 3 hygiene-
checker string-literal test inputs and 4 prose mentions in comments).

tests/unit/gateway/test_pr_gate_posts_review.py

@@ -15,7 +15,7 @@ import pytest
 from roboco.services.gateway.choreographer import Choreographer, ChoreographerDeps
 
 
-def _make_choreographer(git: AsyncMock) -> Choreographer:
+def _make_choreographer(git: AsyncMock) -> Any:
     base: dict[str, Any] = {
         "task": AsyncMock(),
         "work_session": AsyncMock(),
@@ -25,9 +25,9 @@ def _make_choreographer(git: AsyncMock) -> Choreographer:
         "audit": AsyncMock(),
         "evidence_repo": AsyncMock(),
     }
-    c = Choreographer(ChoreographerDeps(**base))
+    c: Any = Choreographer(ChoreographerDeps(**base))
     # _project_slug_for hits the project service; stub it for the unit.
-    c._project_slug_for = AsyncMock(return_value="proj")  # type: ignore[method-assign]
+    c._project_slug_for = AsyncMock(return_value="proj")
     return c