feat(cli+broker): three-tier peer removal: disconnect, kick, ban

Broker (apps/broker/src/index.ts)
- Unified disconnect/kick handler uses close code 1000 for disconnect
  (CLI auto-reconnects) vs 4001 for kick (CLI exits, no reconnect).
- Ban now closes with code 4002.
- Hello handler: revoked members get a specific 'revoked' error with a
  'Contact the mesh owner to rejoin' message, then ws.close(4002).
  Previously banned users saw the generic 'unauthorized' error.
- list_bans handler returns { name, pubkey, revokedAt } for each
  revoked member.

CLI (apps/cli)
- ws-client: close codes 4001 and 4002 set .closed = true and stash
  .terminalClose so callers can surface a friendly message instead of
  the low-level 'ws terminal close' error. Revoked error in hello is
  also captured as a terminal close.
- withMesh catches terminalClose and prints:
  4001 → 'Kicked from this mesh. Run claudemesh to rejoin.'
  4002 → the broker's 'Contact the mesh owner to rejoin.' message
- kick.ts now exports runDisconnect + runKick with clear hints:
  'disconnect' → 'They will auto-reconnect within seconds.'
  'kick'       → 'They can rejoin anytime by running claudemesh.'
- cli.ts adds 'disconnect' dispatch; HELP updated.

Semantics:
  disconnect: session reset, no DB state, auto-reconnects
  kick      : session ends, no DB state, user must manually rejoin
  ban       : session ends + revokedAt set, cannot rejoin until unban

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

apps/cli/package.json

@@ -1,6 +1,6 @@
 {
   "name": "claudemesh-cli",
-  "version": "1.0.0",
+  "version": "1.0.0-alpha.43",
   "description": "Peer mesh for Claude Code sessions — CLI + MCP server.",
   "keywords": [
     "claude-code",