Add can_access_table check to GET /api/catalog/profile/{table_name} and
POST /api/catalog/profile/{table_name}/refresh, returning 403 for
unauthorized tables. Update test_api_complete to cover new 403 behaviour
and fix the existing 404 test to use admin token.
Prevents environment variable leaking between tests. All DATA_DIR,
JWT_SECRET_KEY, and SCRIPT_TIMEOUT assignments in fixtures now use
monkeypatch.setenv() which auto-reverts after each test. Removes
manual os.environ.pop() cleanup lines.
