fix(cli): short-circuit join <slug> when already a member (alpha.41)

If the arg isn't a URL and matches a mesh already in local config,
print a hint pointing at `launch --mesh <slug>` instead of treating
the slug as an invite code. Avoids the 501 invite_v2_disabled confusion
when users try to "enter" a mesh they already own.

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-alpha.40",
+  "version": "1.0.0-alpha.41",
   "description": "Peer mesh for Claude Code sessions — CLI + MCP server.",
   "keywords": [
     "claude-code",