fix: Use correct ProseMirror mark types (strong/em)

Outline schema uses:
- "strong" not "bold"
- "em" not "italic"

Error was: "RangeError: There is no mark type bold in this schema"

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

package.json

@@ -1,6 +1,6 @@
 {
   "name": "mcp-outline-postgresql",
-  "version": "1.3.14",
+  "version": "1.3.15",
   "description": "MCP Server for Outline Wiki via PostgreSQL direct access",
   "main": "dist/index.js",
   "scripts": {