feat: implement automatic static map image generation

- Add html-to-image for capturing map container with markers
- Auto-generate map image on page/marker save via hooks
- Use flag system (.regenerate-map-image) to trigger generation on Panel reload
- Create file using Kirby API for proper indexing
- Add mapStaticImage field in blueprint to display generated image
- Wait for map to be fully loaded before capture
- Capture entire container (map + custom markers)
- Filter MapLibre controls from capture

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

public/site/blueprints/pages/map.yml

@@ -19,6 +19,14 @@ columns:
             defaultCenter: [43.836699, 4.360054]
             defaultZoom: 13
             maxMarkers: 50
+          mapStaticImage:
+            label: Image statique générée
+            type: files
+            multiple: false
+            query: page.files.filterBy("name", "map-static")
+            layout: cards
+            disabled: true
+            help: Cette image est automatiquement générée à la sauvegarde de la page ou d'un marqueur
   sidebar:
     width: 1/3
     sections: