fix: judge camera catalog trimming by region, not by returned cameras

Coverage was checked only for packs among the cameras found, so an area
whose cameras were all trimmed away answered zero cameras, complete. The
catalog now reports where each trimmed pack's cameras are, and the tool
marks an answer partial whenever its area overlaps that region.

src/tools/queries/media.test.mjs

@@ -282,3 +282,43 @@ test('cameras from a trimmed catalog pack are reported as partial', async () =>
     /\(the catalog serves only some cameras here: 250 of 900 from tfl\)\.$/,
   );
 });
+
+test('an area the catalog trimmed away entirely is not reported complete', async () => {
+  const catalog = composeCatalog({
+    tools: coreTools,
+    services: {
+      cctv: {
+        getCatalog: async () => ({
+          trimmedPacks: [
+            {
+              pack: 'tfl',
+              available: 900,
+              served: 250,
+              region: { west: -0.6, south: 51.3, east: 0.3, north: 51.7 },
+            },
+          ],
+          // Every served camera is in central London, none in the suburb.
+          sources: [
+            {
+              id: 'jam-1',
+              name: 'Strand',
+              lat: 51.51,
+              lon: -0.12,
+              pack: 'tfl',
+            },
+          ],
+        }),
+      },
+    },
+  });
+  const suburb = await catalog.call('find_cctv_cameras', {
+    area: { lat: 51.4, lon: -0.5, radius_km: 3 },
+  });
+  assert.equal(suburb.data.rows.length, 0);
+  assert.equal(suburb.data.complete, false);
+  assert.match(suburb.summary, /250 of 900 from tfl/);
+  const elsewhere = await catalog.call('find_cctv_cameras', {
+    area: { lat: 40.7, lon: -74, radius_km: 3 },
+  });
+  assert.equal(elsewhere.data.complete, true);
+});