fix: add polling and reset handling for single mode coordinates

Enhanced coordinate synchronization in single mode to handle Panel
actions like "Supprimer" (reset to saved values).

Issues Fixed:
- Marker not updating when clicking "Supprimer" button in Panel
- Panel "Supprimer" restores saved coordinates but marker didn't move
- No detection of programmatic field value changes

Solution:
- Add MutationObserver to detect attribute changes on input fields
- Add 500ms polling as fallback for value detection
- Add nextTick() for reactive updates to ensure proper timing
- Handle coordinate reset: when invalid, return to default center
- Proper cleanup with onBeforeUnmount for observers and intervals

Behavior:
- User changes field → marker updates immediately
- User drags marker → fields update immediately
- User clicks "Supprimer" → marker returns to saved position
- Fields cleared → marker disappears, map resets to default center

Technical Details:
- MutationObserver watches 'value' attribute on lat/lon inputs
- Polling checks every 500ms for changes missed by events
- Watcher uses nextTick() to ensure DOM updates complete
- All event listeners and observers properly cleaned up on unmount

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

public/site/plugins/map-editor/src/components/field/MapEditor.vue

@@ -36,7 +36,7 @@
 </template>
 
 <script>
-import { ref, computed, watch, onMounted, nextTick } from 'vue';
+import { ref, computed, watch, onMounted, onBeforeUnmount, nextTick } from 'vue';
 import MapPreview from '../map/MapPreview.vue';
 import MarkerList from '../map/MarkerList.vue';
 import { useMarkersApi } from '../../composables/useMarkersApi.js';
@@ -191,6 +191,7 @@ export default {
         // Watch for changes in the form fields
         const form = document.querySelector('.k-form');
         if (form) {
+          // Listen to input events
           form.addEventListener('input', (e) => {
             if (e.target.name && (e.target.name.includes('latitude') || e.target.name.includes('longitude'))) {
               const newCoords = getCoordinatesFromForm();
@@ -198,6 +199,39 @@ export default {
               singleLon.value = newCoords.lon;
             }
           });
+
+          // Also use MutationObserver to detect value changes (e.g., from "Supprimer" button)
+          const latInput = form.querySelector('input[name*="latitude"]');
+          const lonInput = form.querySelector('input[name*="longitude"]');
+
+          if (latInput && lonInput) {
+            const observer = new MutationObserver(() => {
+              const newCoords = getCoordinatesFromForm();
+              if (newCoords.lat !== singleLat.value || newCoords.lon !== singleLon.value) {
+                singleLat.value = newCoords.lat;
+                singleLon.value = newCoords.lon;
+              }
+            });
+
+            // Observe attribute changes (value attribute)
+            observer.observe(latInput, { attributes: true, attributeFilter: ['value'] });
+            observer.observe(lonInput, { attributes: true, attributeFilter: ['value'] });
+
+            // Also poll periodically as a fallback
+            const pollInterval = setInterval(() => {
+              const newCoords = getCoordinatesFromForm();
+              if (newCoords.lat !== singleLat.value || newCoords.lon !== singleLon.value) {
+                singleLat.value = newCoords.lat;
+                singleLon.value = newCoords.lon;
+              }
+            }, 500);
+
+            // Cleanup on unmount
+            onBeforeUnmount(() => {
+              observer.disconnect();
+              clearInterval(pollInterval);
+            });
+          }
         }
       }
 
@@ -228,9 +262,23 @@ export default {
         if (props.mode === 'single') {
           // Center map on new position if valid
           if (!isNaN(lat) && !isNaN(lon) && lat !== null && lon !== null && lat !== 0 && lon !== 0) {
+            // Force immediate reactivity
+            nextTick(() => {
               if (mapPreview.value && mapPreview.value.centerOnPosition) {
                 mapPreview.value.centerOnPosition(lat, lon);
               }
+            });
+          } else {
+            // Coordinates are invalid/cleared - reset to default center
+            center.value = {
+              lat: props.defaultCenter[0],
+              lon: props.defaultCenter[1]
+            };
+            nextTick(() => {
+              if (mapPreview.value && mapPreview.value.centerOnPosition) {
+                mapPreview.value.centerOnPosition(center.value.lat, center.value.lon);
+              }
+            });
           }
         }
       }