fix(cli): send_message hard-fails on unknown peer name; dedup-annotate list_peers

Two bugs that combined to make Claude's peer-send look successful even
when the recipient didn't exist:

1. resolveClient fell through to 'let the broker try' when a single
   mesh was joined and the name didn't match any peer. The broker
   queued the message against the literal unknown string, matched no
   peer in fan-out, but returned a messageId — so the CLI reported
   '✓ lezg → msgId' for a peer that was never there.

   Now: refuse to send, list the known peer names.

2. list_peers showed the same pubkey multiple times with different
   display_names (one per live session) without hinting that they
   were the same member — so Claude treated them as distinct people.

   Now: annotate with '[shares key with N other session(s)]' so the
   caller understands one pubkey = one identity.

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

apps/cli/package.json

@@ -1,6 +1,6 @@
 {
   "name": "claudemesh-cli",
-  "version": "1.0.0-alpha.32",
+  "version": "1.0.0-alpha.33",
   "description": "Peer mesh for Claude Code sessions — CLI + MCP server.",
   "keywords": [
     "claude-code",