fix(mcp): make opennest server launchable on any machine

.mcp.json pointed at C:/Users/AJ/.claude/mcp/OpenNest.Mcp/run.cmd, a
profile path and wrapper script that only existed on one machine, so the
server failed with CONNECTION_CLOSED everywhere else. Launch the published
exe via ${USERPROFILE} instead.

Also route console logging to stderr: the host's default console logger
wrote to stdout, interleaving log lines with the JSON-RPC stream.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

.mcp.json

@@ -1,8 +1,8 @@
 {
   "mcpServers": {
     "opennest": {
-      "command": "cmd",
-      "args": ["/c", "C:/Users/AJ/.claude/mcp/OpenNest.Mcp/run.cmd"]
+      "command": "${USERPROFILE}/.claude/mcp/OpenNest.Mcp/OpenNest.Mcp.exe",
+      "args": []
     }
   }
 }