feat: change default port from 47822 to 37849 (v1.2.0)

47822 collided with ClaudeDo.Worker.exe on at least one user's machine.
37849 is high, registered to nobody, and avoids the prior conflict.
Both the Node port and the .NET port move together (still
wire-compatible). Defaults change only — if a user has a custom port
in mailbox.json, that stays.

node/src/cli.ts

@@ -271,7 +271,7 @@ program
 program
   .command("mcp-stdio")
   .description(
-    "Run a stdio MCP server that proxies tool calls to the local daemon's REST API. The daemon URL comes from $CLAUDE_MAILBOX_URL (default http://127.0.0.1:47822). Used by the Claude Code plugin's .mcp.json so the URL is configurable per machine without env-substitution in the URL field.",
+    "Run a stdio MCP server that proxies tool calls to the local daemon's REST API. The daemon URL comes from $CLAUDE_MAILBOX_URL (default http://127.0.0.1:37849). Used by the Claude Code plugin's .mcp.json so the URL is configurable per machine without env-substitution in the URL field.",
   )
   .action(async () => {
     try {