feat(maps): add notes input to map pin placement popup

The map_markers backend has accepted a `notes` column since PR #770 and
the popup display path was wired up to render it (commit 6328256), but
the placement UI never got an input. Result: notes are stored,
displayed when present, and impossible to actually enter via the UI.

Add a notes textarea below the name input in the placement popup,
thread the value through `addMarker` and `createMapMarker`, and trim +
null-coalesce on save. Notes display in the marker popup on click is
unchanged and now actually reachable.

- admin/inertia/lib/api.ts: extend createMapMarker request type with
  optional notes
- admin/inertia/hooks/useMapMarkers.ts: addMarker accepts and forwards
  notes (response already populated notes into local state, so no
  display-side change needed)
- admin/inertia/components/maps/MapComponent.tsx: markerNotes state,
  textarea after name input, threaded into handleSaveMarker

Edit-mode for existing markers (so users can backfill notes on
already-placed pins) is intentionally out of scope here - selected-marker
popup is still read-only. That's a follow-up PR if there's demand.

admin/inertia/components/maps/MapComponent.tsx

@@ -72,6 +72,7 @@ export default function MapComponent({
   const [isDraggingMap, setIsDraggingMap] = useState(false)
   const [placingMarker, setPlacingMarker] = useState<{ lng: number; lat: number } | null>(null)
   const [markerName, setMarkerName] = useState('')
+  const [markerNotes, setMarkerNotes] = useState('')
   const [markerColor, setMarkerColor] = useState<PinColorId>('orange')
   const [selectedMarkerId, setSelectedMarkerId] = useState<number | null>(null)
 
@@ -153,18 +154,27 @@ export default function MapComponent({
   const handleMapClick = useCallback((e: MapLayerMouseEvent) => {
     setPlacingMarker({ lng: e.lngLat.lng, lat: e.lngLat.lat })
     setMarkerName('')
+    setMarkerNotes('')
     setMarkerColor('orange')
     setSelectedMarkerId(null)
   }, [])
 
   const handleSaveMarker = useCallback(() => {
     if (placingMarker && markerName.trim()) {
-      addMarker(markerName.trim(), placingMarker.lng, placingMarker.lat, markerColor)
+      const trimmedNotes = markerNotes.trim()
+      addMarker(
+        markerName.trim(),
+        placingMarker.lng,
+        placingMarker.lat,
+        markerColor,
+        trimmedNotes ? trimmedNotes : null
+      )
       setPlacingMarker(null)
       setMarkerName('')
+      setMarkerNotes('')
       setMarkerColor('orange')
     }
-  }, [placingMarker, markerName, markerColor, addMarker])
+  }, [placingMarker, markerName, markerNotes, markerColor, addMarker])
 
   const handleFlyTo = useCallback((longitude: number, latitude: number) => {
     mapRef.current?.flyTo({ center: [longitude, latitude], zoom: 12, duration: 1500 })
@@ -317,6 +327,17 @@ export default function MapComponent({
                   className="block w-full rounded border border-gray-300 px-2 py-1 text-sm placeholder:text-gray-400 focus:outline-none focus:border-gray-500"
                 />
 
+                <textarea
+                  placeholder="Notes (optional)"
+                  value={markerNotes}
+                  onChange={(e) => setMarkerNotes(e.target.value)}
+                  onKeyDown={(e) => {
+                    if (e.key === 'Escape') setPlacingMarker(null)
+                  }}
+                  rows={2}
+                  className="mt-1.5 block w-full resize-y rounded border border-gray-300 px-2 py-1 text-sm placeholder:text-gray-400 focus:outline-none focus:border-gray-500"
+                />
+
                 <div className="mt-1.5 flex gap-1 items-center">
                   {PIN_COLORS.map((c) => (
                     <button

admin/inertia/hooks/useMapMarkers.ts

@@ -47,8 +47,14 @@ export function useMapMarkers() {
   }, [])
 
   const addMarker = useCallback(
-    async (name: string, longitude: number, latitude: number, color: PinColorId = 'orange') => {
-      const result = await api.createMapMarker({ name, longitude, latitude, color })
+    async (
+      name: string,
+      longitude: number,
+      latitude: number,
+      color: PinColorId = 'orange',
+      notes: string | null = null
+    ) => {
+      const result = await api.createMapMarker({ name, longitude, latitude, color, notes })
       if (result) {
         const marker: MapMarker = {
           id: result.id,

admin/inertia/lib/api.ts

@@ -720,7 +720,7 @@ class API {
     })()
   }
 
-  async createMapMarker(data: { name: string; longitude: number; latitude: number; color?: string }) {
+  async createMapMarker(data: { name: string; longitude: number; latitude: number; color?: string; notes?: string | null }) {
     return catchInternal(async () => {
       const response = await this.client.post<
         { id: number; name: string; longitude: number; latitude: number; color: string; notes: string | null; created_at: string }