feat(audit): P1 cross-tenant/RBAC tests, P3 test fixes, P2/P3 frontend fixes

- P1-Tests: 12 test files with new cross-tenant isolation + RBAC tests
- P3-Tests: 8 fixes (duplicate fixtures, sys.path.insert, unused imports, KeyError)
- P3-Frontend: LucideIcons → ICON_MAP (2 files), inline styles → Tailwind (2 files)
- P3-Frontend: DOMPurify for iframe XSS, redundant regex removed, console.log → console.debug
- P2-Frontend: 2 notification API TODOs retained (requires larger refactor)
- conftest.py: create_no_perm_user helper added
- pyproject.toml: pythonpath for scripts/ added
- All checks green: ruff 0, F821 0, tsc 0, app 495 routes, cross-plugin 0

tests/test_agent_subtasks.py

@@ -26,11 +26,6 @@ def db_setup():
     yield
 
 
-@pytest.fixture(autouse=True)
-def clean_tables(db_setup):
-    """No-op override of conftest clean_tables."""
-    yield
-
 @pytest.fixture(autouse=True)
 def clean_tables(db_setup):
     """No-op override of conftest clean_tables."""