Root cause Blocker #2: `import app.workers.tasks.scrape_cadastre` at module
top-level REBOUND `app` from FastAPI instance (line 14) to the Python package.
All subsequent `app.dependency_overrides[get_db] = ...` failed with
AttributeError because `app` was now the namespace module.
Fix: probe module availability with importlib.util.find_spec — does not
import or rebind names. FastAPI `app` instance stays intact.
All 28 cadastre tests pass locally.
Blocker #1: rename tile_width/tile_height → tile_size in generate_grid_click_points.
Callers in bulk_harvest.py and test_cadastre_bulk.py used tile_size; def had
tile_width+tile_height → TypeError at runtime.
Blocker #2 (10 failures in test_admin_cadastre.py) was side-effect of #1:
TypeError at import chain (app.main → admin_cadastre → bulk_harvest)
broke FastAPI app load → dependency_overrides AttributeError. Now resolved.
Also register `slow` pytest marker in pyproject.toml to suppress
PytestUnknownMarkWarning.
