fix(edit_diagram): implement cascade delete for children and edges (#451)

* fix(edit_diagram): implement cascade delete for children and edges

- Add automatic cascade deletion when deleting a cell
- Recursively delete all child cells (parent attribute references)
- Delete all edges referencing deleted cells (source/target)
- Skip silently if cell already deleted (handles AI redundant ops)
- Update prompts to inform AI about cascade behavior

Fixes #450

* fix: add root cell protection and sync MCP server cascade delete

- Add protection for root cells '0' and '1' to prevent full diagram wipe
- Sync MCP server with main app's cascade delete logic
- Both lib/utils.ts and packages/mcp-server now have identical delete behavior

* chore(mcp): bump version to 0.1.9

* fix(cascade-delete): recursively collect edge children (labels)

- Change from cellsToDelete.add(edgeId) to collectDescendants(edgeId)
- Fixes orphaned edge labels causing draw.io to crash/clear canvas
- Edge labels (parent=edgeId) are now deleted with their parent edge

packages/mcp-server/package.json

@@ -1,6 +1,6 @@
 {
     "name": "@next-ai-drawio/mcp-server",
-    "version": "0.1.8",
+    "version": "0.1.10",
     "description": "MCP server for Next AI Draw.io - AI-powered diagram generation with real-time browser preview",
     "type": "module",
     "main": "dist/index.js",