v0.9.5: The Voltron Update — modular architecture, stable IDs, parallelized boot

- Parallelized startup (60s → 15s) via ThreadPoolExecutor
- Adaptive polling engine with ETag caching (no more bbox interrupts)
- useCallback optimization for interpolation functions
- Sliding LAYERS/INTEL edge panels replace bulky Record Panel
- Modular fetcher architecture (flights, geo, infrastructure, financial, earth_observation)
- Stable entity IDs for GDELT & News popups (PR #63, credit @csysp)
- Admin auth (X-Admin-Key), rate limiting (slowapi), auto-updater
- Docker Swarm secrets support, env_check.py validation
- 85+ vitest tests, CI pipeline, geoJSON builder extraction
- Server-side viewport bbox filtering reduces payloads 80%+

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

Former-commit-id: f2883150b5bc78ebc139d89cc966a76f7d7c0408

frontend/src/hooks/useReverseGeocode.ts

@@ -0,0 +1,66 @@
+import { useCallback, useState, useRef } from "react";
+import { GEOCODE_THROTTLE_MS, GEOCODE_DISTANCE_THRESHOLD, GEOCODE_CACHE_SIZE } from "@/lib/constants";
+
+export function useReverseGeocode() {
+  const [mouseCoords, setMouseCoords] = useState<{ lat: number; lng: number } | null>(null);
+  const [locationLabel, setLocationLabel] = useState('');
+  const geocodeCache = useRef<Map<string, string>>(new Map());
+  const geocodeTimer = useRef<ReturnType<typeof setTimeout> | null>(null);
+  const lastGeocodedPos = useRef<{ lat: number; lng: number } | null>(null);
+  const geocodeAbort = useRef<AbortController | null>(null);
+
+  const handleMouseCoords = useCallback((coords: { lat: number; lng: number }) => {
+    setMouseCoords(coords);
+
+    if (geocodeTimer.current) clearTimeout(geocodeTimer.current);
+    geocodeTimer.current = setTimeout(async () => {
+      if (lastGeocodedPos.current) {
+        const dLat = Math.abs(coords.lat - lastGeocodedPos.current.lat);
+        const dLng = Math.abs(coords.lng - lastGeocodedPos.current.lng);
+        if (dLat < GEOCODE_DISTANCE_THRESHOLD && dLng < GEOCODE_DISTANCE_THRESHOLD) return;
+      }
+
+      const gridKey = `${(coords.lat).toFixed(2)},${(coords.lng).toFixed(2)}`;
+      const cached = geocodeCache.current.get(gridKey);
+      if (cached) {
+        setLocationLabel(cached);
+        lastGeocodedPos.current = coords;
+        return;
+      }
+
+      if (geocodeAbort.current) geocodeAbort.current.abort();
+      geocodeAbort.current = new AbortController();
+
+      try {
+        const res = await fetch(
+          `https://nominatim.openstreetmap.org/reverse?lat=${coords.lat}&lon=${coords.lng}&format=json&zoom=10&addressdetails=1`,
+          { headers: { 'Accept-Language': 'en' }, signal: geocodeAbort.current.signal }
+        );
+        if (res.ok) {
+          const data = await res.json();
+          const addr = data.address || {};
+          const city = addr.city || addr.town || addr.village || addr.county || '';
+          const state = addr.state || addr.region || '';
+          const country = addr.country || '';
+          const parts = [city, state, country].filter(Boolean);
+          const label = parts.join(', ') || data.display_name?.split(',').slice(0, 3).join(',') || 'Unknown';
+
+          if (geocodeCache.current.size > GEOCODE_CACHE_SIZE) {
+            const iter = geocodeCache.current.keys();
+            for (let i = 0; i < 100; i++) {
+              const key = iter.next().value;
+              if (key !== undefined) geocodeCache.current.delete(key);
+            }
+          }
+          geocodeCache.current.set(gridKey, label);
+          setLocationLabel(label);
+          lastGeocodedPos.current = coords;
+        }
+      } catch (e: any) {
+        if (e.name !== 'AbortError') { /* Silently fail - keep last label */ }
+      }
+    }, GEOCODE_THROTTLE_MS);
+  }, []);
+
+  return { mouseCoords, locationLabel, handleMouseCoords };
+}