feat(ui): surface review readiness and blockers

Add readiness hints, blocker summaries, and progress cues across
the dataset review workspace to clarify partial recovery and
launch gating states.

Highlight read-only preview snapshots, pending semantic review,
clarification queue status, and unresolved validation blockers to
guide the next recommended action.

Document known limitations in backend test doubles so permission,
task dispatch, and uncovered persistence branches are explicit.

backend/src/api/routes/__tests__/test_datasets.py

@@ -31,6 +31,10 @@ mock_user.roles.append(admin_role)
 
 @pytest.fixture(autouse=True)
 def mock_deps():
+    """Bare MagicMock — no spec guards. All service method calls succeed silently.
+
+    Authorization, data integrity, and error paths are invisible to this fixture.
+    """
     # @INVARIANT: unconstrained mock — no spec= enforced; attribute typos will silently pass
     config_manager = MagicMock()
     # @INVARIANT: unconstrained mock — no spec= enforced; attribute typos will silently pass