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/plugins/map-editor/package.json

@@ -8,8 +8,10 @@
     "build": "npx -y kirbyup src/index.js"
   },
   "dependencies": {
+    "html-to-image": "^1.11.13",
+    "js-yaml": "^4.1.0",
     "maplibre-gl": "^3.6.0",
-    "js-yaml": "^4.1.0"
+    "maplibre-gl-map-to-image": "^1.2.0"
   },
   "devDependencies": {
     "kirbyup": "^3.3.0"