feat(travel): 좌표 없는 커스텀 지역에 항상 "위치 지정" 버튼 표시

지역 변경 직후뿐 아니라, 앨범의 지역이 좌표 미지정 커스텀
지역이면 헤더에 핀 버튼을 상시 노출. 기존 좌표가 있으면
RegionPinPicker에 초기값으로 전달.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

src/pages/travel/AlbumDetail.jsx

@@ -189,6 +189,31 @@ export default function AlbumDetail({
 
   /* ── Derived ── */
   const regionAccent = getRegionAccent(album?.region || album?.id || '');
+
+  // Determine if the album's region is a custom region missing coordinates
+  const currentRegionId = savedRegionId || album?.region || album?.id || '';
+  const needsPin = useMemo(() => {
+    if (!currentRegionId || !regions?.features) return false;
+    const feature = regions.features.find((f) => {
+      const rid = f.properties?.id || f.properties?.name || '';
+      return rid.toLowerCase() === currentRegionId.toLowerCase();
+    });
+    if (!feature) return true; // region not in GeoJSON at all → needs pin
+    if (feature.properties?.custom && !feature.geometry) return true; // custom without coords
+    return false;
+  }, [currentRegionId, regions]);
+
+  // Coords of existing pin (for initialCoords in picker)
+  const existingCoords = useMemo(() => {
+    if (!currentRegionId || !regions?.features) return null;
+    const feature = regions.features.find((f) => {
+      const rid = f.properties?.id || f.properties?.name || '';
+      return rid.toLowerCase() === currentRegionId.toLowerCase();
+    });
+    if (feature?.geometry?.type === 'Point') return feature.geometry.coordinates;
+    return null;
+  }, [currentRegionId, regions]);
+
   const photoCountLabel = photoSummary?.total
     ? `${photoSummary.total} photos`
     : photos?.length
@@ -323,7 +348,7 @@ export default function AlbumDetail({
                     <path d="M7.5 1.5l1 1-5.5 5.5H2V7z" stroke="currentColor" strokeWidth="0.8" strokeLinejoin="round"/>
                   </svg>
                 </button>
-                {regionMsg?.type === 'ok' && savedRegionId && (
+                {(needsPin || (regionMsg?.type === 'ok' && savedRegionId)) && (
                   <button
                     className="album-detail__pin-btn"
                     onClick={handleOpenPinPicker}
@@ -349,11 +374,11 @@ export default function AlbumDetail({
       </div>
 
       {/* Pin Picker */}
-      {pinPickerOpen && savedRegionId && (
+      {pinPickerOpen && currentRegionId && (
         <RegionPinPicker
-          regionId={savedRegionId}
-          regionName={savedRegionId}
-          initialCoords={null}
+          regionId={currentRegionId}
+          regionName={album?.regionName || currentRegionId}
+          initialCoords={existingCoords}
           accent={regionAccent}
           onSave={handlePinSave}
           onClose={() => setPinPickerOpen(false)}