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/README.md

@@ -25,7 +25,7 @@ Run the printed command, then restart Claude Code.
 ## Join a mesh
 
 ```sh
-claudemesh join ic://join/BASE64URL...
+claudemesh join https://claudemesh.com/join/<token>
 ```
 
 The invite link is generated by whoever runs the mesh. It bundles the
@@ -37,7 +37,7 @@ the result to `~/.claudemesh/config.json`.
 
 ```sh
 claudemesh install         # print MCP registration command
-claudemesh join <link>     # join a mesh via invite link
+claudemesh join <url>      # join a mesh via invite URL
 claudemesh list            # show joined meshes + identities
 claudemesh leave <slug>    # leave a mesh
 claudemesh mcp             # start MCP server (stdio — Claude Code only)