Implement story 1.5: provisioning execution tile download cache validation wifi kill

Add tiles.py, airspace.py, wifi.join_home_wifi, portal /submit route, and rewire
provision.py main loop; all tasks and quality gates pass (56 tests, ruff clean).

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

tests/provisioning/test_airspace.py

@@ -0,0 +1,31 @@
+import json
+from pathlib import Path
+from unittest.mock import MagicMock, patch
+
+import pytest
+
+from planemapper.provisioning.airspace import download
+
+
+def test_download_no_api_key(tmp_path: Path, monkeypatch: pytest.MonkeyPatch) -> None:
+    airspace_path = tmp_path / "airspace.geojson"
+    monkeypatch.delenv("OPENAIP_API_KEY", raising=False)
+    with patch("planemapper.provisioning.airspace.AIRSPACE_PATH", airspace_path):
+        download(51.5, -0.1, 100)
+    data = json.loads(airspace_path.read_text())
+    assert data["type"] == "FeatureCollection"
+    assert data["features"] == []
+
+
+def test_download_with_api_key(tmp_path: Path, monkeypatch: pytest.MonkeyPatch) -> None:
+    airspace_path = tmp_path / "airspace.geojson"
+    monkeypatch.setenv("OPENAIP_API_KEY", "testkey123")
+    mock_resp = MagicMock()
+    mock_resp.ok = True
+    mock_resp.text = '{"type":"FeatureCollection","features":[]}'
+    with (
+        patch("planemapper.provisioning.airspace.requests.get", return_value=mock_resp),
+        patch("planemapper.provisioning.airspace.AIRSPACE_PATH", airspace_path),
+    ):
+        download(51.5, -0.1, 100)
+    assert airspace_path.exists()