fix(cli): v0.5.7 — event loop keepalive for stdout flush

Node.js stdout to a pipe is buffered. Without periodic event loop
activity, WS callback → server.notification() → stdout.write() may
not flush until the next I/O event. A 1s setInterval (NOT unref'd)
keeps the event loop ticking so notifications flush immediately.

This is why claude-intercom worked: its 1s HTTP poll kept the event
loop active as a side effect. Claudemesh's passive WS listener let
the event loop settle, causing stdout to buffer indefinitely.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

apps/cli/package.json

@@ -1,6 +1,6 @@
 {
   "name": "claudemesh-cli",
-  "version": "0.5.6",
+  "version": "0.5.7",
   "description": "Claude Code MCP client for claudemesh — peer mesh messaging between Claude sessions.",
   "keywords": [
     "claude-code",