feat: Add Markdown to ProseMirror converter

- New converter supports headings, lists, blockquotes, code blocks
- Documents now render with proper formatting in Outline
- Auto-update collection documentStructure on document creation
- Documents appear in sidebar automatically

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

package-lock.json

@@ -1,12 +1,12 @@
 {
   "name": "mcp-outline-postgresql",
-  "version": "1.3.13",
+  "version": "1.3.14",
   "lockfileVersion": 3,
   "requires": true,
   "packages": {
     "": {
       "name": "mcp-outline-postgresql",
-      "version": "1.3.13",
+      "version": "1.3.14",
       "license": "MIT",
       "dependencies": {
         "@modelcontextprotocol/sdk": "^1.0.0",