feat: implement MCP server plugin v1.0.0

Add HTTP-based MCP server exposing 20 Joplin tools (notes, notebooks,
tags, search) via StreamableHTTPServerTransport. Includes configurable
host/port settings, CORS support, and session management.

- src/index.ts: Plugin registration and settings UI
- src/server.ts: MCP HTTP server with StreamableHTTP transport
- src/tools.ts: 20 MCP tool definitions for Joplin operations
- LICENSE: MIT license
- CHANGELOG.md: v1.0.0 changelog entry
- README.md: Comprehensive documentation

package.json

@@ -28,6 +28,6 @@
   },
   "dependencies": {
     "@modelcontextprotocol/sdk": "^1.29.0",
-    "zod": "^4.4.3"
+    "zod": "^3.25.0"
   }
 }