feat: unified photo provider abstraction layer (#584)

Introduce trek_photos as central photo registry. Frontend uses
/api/photos/:id/:kind instead of provider-specific URLs. Adding
a new photo provider is now backend-only work.

- New trek_photos table (migration 98) with photo_id FK in
  trip_photos and journey_photos
- Unified /api/photos/:id/thumbnail|original|info endpoint
- photoResolverService for central resolution and streaming
- ProviderPicker: add "All Photos" tab, rename tabs, fix i18n
- Localize all hardcoded strings in JourneyDetailPage (14 langs)
- Fix date formatting to use browser locale instead of hardcoded 'en'
- Journey stats as styled tile cards

client/src/components/Planner/PlaceFormModal.tsx

@@ -286,7 +286,7 @@ export default function PlaceFormModal({
             onChange={e => handleChange('description', e.target.value)}
             rows={2}
             placeholder={t('places.formDescriptionPlaceholder')}
-            className="form-input" style={{ resize: 'none' }}
+            className="form-input" style={{ resize: 'vertical' }}
           />
         </div>