fix: drag handle resolve container blocks + menu popup clamp viewport

- Drag handle résout les blocs conteneurs (columns, toggle, callout) au lieu du paragraphe intérieur
- Delete agit sur tout le bloc conteneur, pas juste le paragraphe
- Menu popup (block action menu) clampé dans le viewport (Math.min + overflow auto)
- Drag handle clamped dans le viewport via MutationObserver + scroll/resize

memento-note/lib/editor/block-at-drag-handle.ts

@@ -21,5 +21,20 @@ export function resolveBlockAtDragHandle(editor: Editor): { node: PMNode; pos: n
   const node = editor.state.doc.nodeAt(blockPos)
   if (!node) return null
 
+  // Climb up to container blocks (columns, toggleBlock, calloutBlock)
+  // so the drag handle operates on the whole container, not inner paragraphs
+  const CONTAINER_TYPES = ['columns', 'toggleBlock', 'calloutBlock']
+  const $blockPos = editor.state.doc.resolve(blockPos)
+  for (let depth = $blockPos.depth; depth > 0; depth--) {
+    const ancestor = $blockPos.node(depth)
+    if (CONTAINER_TYPES.includes(ancestor.type.name)) {
+      const containerPos = $blockPos.before(depth)
+      const containerNode = editor.state.doc.nodeAt(containerPos)
+      if (containerNode) {
+        return { node: containerNode, pos: containerPos }
+      }
+    }
+  }
+
   return { node, pos: blockPos }
 }