Implement story 1.4: location resolution ICAO and address

Adds location.resolve() with ICAO CSV lookup and Nominatim geocoding,
POST /find-location portal route with inline confirmation/error display,
and full test coverage with mocked network calls.

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

tests/provisioning/test_location.py

@@ -1,2 +1,55 @@
-def test_placeholder() -> None:
-    pass
+from unittest.mock import MagicMock, patch
+
+import pytest
+
+from planemapper.provisioning.location import resolve
+
+
+def test_icao_lookup_hit_egll() -> None:
+    lat, lon, name = resolve("EGLL")
+    assert isinstance(lat, float)
+    assert isinstance(lon, float)
+    assert isinstance(name, str)
+    assert 50.0 < lat < 52.0  # Heathrow is ~51.47°N
+    assert -1.0 < lon < 0.0  # and ~0.46°W
+
+
+def test_icao_lookup_case_insensitive() -> None:
+    lat, lon, name = resolve("egll")
+    assert lat != 0.0
+
+
+def test_icao_lookup_miss_raises_value_error() -> None:
+    with pytest.raises(ValueError, match="ICAO code not found"):
+        resolve("ZZZZ")
+
+
+def test_nominatim_success() -> None:
+    mock_resp = MagicMock()
+    mock_resp.json.return_value = [
+        {"lat": "51.5", "lon": "-0.1", "display_name": "London, England"}
+    ]
+    with patch("planemapper.provisioning.location.requests.get", return_value=mock_resp):
+        lat, lon, name = resolve("OX1 1AA")
+    assert lat == 51.5
+    assert lon == -0.1
+    assert name == "London, England"
+
+
+def test_nominatim_empty_raises_value_error() -> None:
+    mock_resp = MagicMock()
+    mock_resp.json.return_value = []
+    with patch("planemapper.provisioning.location.requests.get", return_value=mock_resp):
+        with pytest.raises(ValueError, match="Location not found"):
+            resolve("nonsense query that returns nothing")
+
+
+def test_nominatim_called_with_user_agent() -> None:
+    mock_resp = MagicMock()
+    mock_resp.json.return_value = [{"lat": "51.5", "lon": "-0.1", "display_name": "London"}]
+    with patch(
+        "planemapper.provisioning.location.requests.get", return_value=mock_resp
+    ) as mock_get:
+        resolve("London")
+    call_kwargs = mock_get.call_args
+    assert "User-Agent" in call_kwargs.kwargs.get("headers", {})