Add MCP server for AI-assisted Stiftung data access

Provides a Model Context Protocol server exposing read-only tools
for Destinatäre, Ländereien, Pächter, Konten, Transaktionen and more.
Includes SSH-based remote connection config in .mcp.json.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

.mcp.json

@@ -0,0 +1,12 @@
+{
+  "mcpServers": {
+    "stiftung": {
+      "command": "ssh",
+      "args": [
+        "-o", "StrictHostKeyChecking=no",
+        "deployment@217.154.84.225",
+        "cd /opt/stiftung && docker compose run --rm -T -e MCP_AUTH_TOKEN=a66d2bf53b83489693a59af6ff0e3dd2a09885b98aced40f6bbb7423a173e173 -e DJANGO_ALLOW_ASYNC_UNSAFE=true mcp"
+      ]
+    }
+  }
+}