fix(cli): v0.5.4 — revert to event-driven push, add Claude Code integration spec

Revert poll-based drain (v0.5.2 overcorrection). Claude Code source
confirms notifications are processed event-driven via React
useEffect, not polled. The WS onPush → server.notification() path
is correct.

Added section 13 to SPEC.md documenting the full Claude Code
notification pipeline, feature gates, priority gating, and common
push delivery issues.

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

apps/cli/package.json

@@ -1,6 +1,6 @@
 {
   "name": "claudemesh-cli",
-  "version": "0.5.3",
+  "version": "0.5.4",
   "description": "Claude Code MCP client for claudemesh — peer mesh messaging between Claude sessions.",
   "keywords": [
     "claude-code",