feat(cli): accept https://claudemesh.com/join/<token> invite URL format

Pairs with claudemesh-2's new /join/[token] landing page. Users can
now paste a clickable HTTPS URL instead of the dev-only ic:// scheme.

apps/cli/src/invite/parse.ts — new extractInviteToken() handles
four input formats before handing the raw base64url token to the
existing parseInviteLink pipeline:
  - https://claudemesh.com/join/<token>   (primary, clickable)
  - https://claudemesh.com/<locale>/join/<token>   (i18n prefix)
  - ic://join/<token>                     (still supported, dev)
  - <raw-token>                           (last resort: bare base64url)

User-facing strings updated to the HTTPS form:
- cli help: "join <url>"
- install success message
- list (no-meshes) hint
- MCP server "no meshes" error
- README.md primary example
- docs/QUICKSTART.md Path A + Path B

Verified extractInviteToken() on all 4 formats — each returns the
same base64url token → same broker /join lookup.

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

apps/cli/src/index.ts

@@ -23,7 +23,7 @@ Usage:
 Commands:
   install         Register claudemesh as a Claude Code MCP server
   uninstall       Remove claudemesh MCP server registration
-  join <link>     Join a mesh via invite link (ic://join/...)
+  join <url>      Join a mesh via https://claudemesh.com/join/... URL
   list            Show all joined meshes
   leave <slug>    Leave a joined mesh
   seed-test-mesh  Dev-only: inject a mesh into config (skips invite flow)