feat: search, multi-stop routing, and route display

Full navigation UI with:
- Search bar with 150ms debounced autocomplete from /api/geocode
- Keyboard navigation (arrow keys, Enter, Escape)
- Exact match badge for verified address results
- Multi-stop list with drag-to-reorder (dnd-kit)
- 10-stop cap with disabled state
- Mode selector (drive/walk/bike)
- Valhalla route display with per-leg color polyline
- Maneuver list with instructions, distance, time remaining
- Click maneuver to fly map to that point
- Optimize stops button (3+ stops, uses /optimized_route)
- Responsive: side panel (desktop ≥768px), bottom sheet (mobile)
- Stop pins: green origin, red destination, blue intermediate
- Pin popup with remove button
- Geolocation permission requested on first route, not on load
- Error handling for unroutable pairs
- nginx proxy for /api/ and /valhalla/ endpoints

Dependencies added: zustand, @dnd-kit/core, @dnd-kit/sortable,
@dnd-kit/utilities

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

src/store.js

@@ -0,0 +1,65 @@
+import { create } from 'zustand'
+
+export const useStore = create((set, get) => ({
+  // ── Search state ──
+  query: '',
+  results: [],
+  searchLoading: false,
+  abortController: null,
+
+  setQuery: (query) => set({ query }),
+  setResults: (results) => set({ results }),
+  setSearchLoading: (loading) => set({ searchLoading: loading }),
+  setAbortController: (ctrl) => set({ abortController: ctrl }),
+
+  // ── Stop list ──
+  stops: [],
+  // Each stop: { id, lat, lon, name, source, matchCode, isOrigin }
+
+  addStop: (stop) => {
+    const { stops } = get()
+    if (stops.length >= 10) return false
+    set({ stops: [...stops, { ...stop, id: crypto.randomUUID() }] })
+    return true
+  },
+
+  removeStop: (id) => {
+    set({ stops: get().stops.filter((s) => s.id !== id) })
+  },
+
+  reorderStops: (newStops) => set({ stops: newStops }),
+
+  clearStops: () => set({ stops: [] }),
+
+  setStops: (stops) => set({ stops }),
+
+  // ── Geolocation ──
+  userLocation: null, // { lat, lon }
+  geoPermission: 'prompt', // 'prompt' | 'granted' | 'denied'
+
+  setUserLocation: (loc) => set({ userLocation: loc }),
+  setGeoPermission: (p) => set({ geoPermission: p }),
+
+  // ── Mode ──
+  mode: 'auto', // 'auto' | 'pedestrian' | 'bicycle'
+  setMode: (mode) => set({ mode }),
+
+  // ── Route ──
+  route: null, // Valhalla response (trip object)
+  routeLoading: false,
+  routeError: null,
+
+  setRoute: (route) => set({ route, routeError: null }),
+  setRouteLoading: (loading) => set({ routeLoading: loading }),
+  setRouteError: (err) => set({ routeError: err, route: null }),
+  clearRoute: () => set({ route: null, routeError: null }),
+
+  // ── UI state ──
+  sheetState: 'half', // 'collapsed' | 'half' | 'full'
+  panelOpen: true,
+  autocompleteOpen: false,
+
+  setSheetState: (s) => set({ sheetState: s }),
+  setPanelOpen: (open) => set({ panelOpen: open }),
+  setAutocompleteOpen: (open) => set({ autocompleteOpen: open }),
+}))