feat(import): selective GPX/KML element import and performance improvements

Add type-selector UI in the file import modal letting users choose which
GPX elements (waypoints, routes, tracks) or KML/KMZ elements (points,
paths) to import. KML LineString placemarks are now imported as path
places with route_geometry.

Performance improvements:
- Extract MemoPlaceRow with React.memo and contentVisibility:auto to cut
  unnecessary re-renders in PlacesSidebar
- Add weatherQueue to cap concurrent weather fetches at 3
- Replace sequential per-place deletes with a single bulkDelete API call
  (new DELETE /places/bulk endpoint + deletePlacesMany service)
- Memoize atlas/photo/weather service calls to avoid redundant requests
- Add multi-select mode to PlacesSidebar for bulk operations

Add large GPX/KML/KMZ fixtures for integration/perf testing and two
profiler analysis scripts under scripts/.

client/src/services/weatherQueue.ts

@@ -0,0 +1,25 @@
+import { weatherApi } from '../api/client'
+
+const MAX_CONCURRENT = 3
+let active = 0
+const queue: Array<() => void> = []
+
+function acquire(): Promise<void> {
+  if (active < MAX_CONCURRENT) { active++; return Promise.resolve() }
+  return new Promise(resolve => queue.push(resolve))
+}
+
+function release(): void {
+  const next = queue.shift()
+  if (next) next()
+  else active--
+}
+
+export async function fetchWeather(lat: number, lng: number, date: string) {
+  await acquire()
+  try {
+    return await weatherApi.get(lat, lng, date)
+  } finally {
+    release()
+  }
+}