feat: integrate meshservice crate into workspace

- Add meshservice to workspace members
- Fix quicprochat-client: add MeshTrace/MeshStats slash commands
- Add integration test: meshservice_tcp_transport
- Document integration points in README and docs/status.md
- Verify shared identity (IdentityKeypair → MeshAddress)

README.md

@@ -84,6 +84,7 @@ quicprochat/
 │   ├── quicprochat-client       # CLI + REPL + TUI (Ratatui)
 │   ├── quicprochat-kt           # Key transparency (Merkle-log, revocation)
 │   ├── quicprochat-p2p          # iroh P2P, mesh identity, store-and-forward
+│   ├── meshservice              # Decentralized service layer (FAPP, housing, wire format)
 │   ├── quicprochat-ffi          # C FFI (libquicprochat_ffi.so)
 │   └── quicprochat-plugin-api   # Dynamic plugin hooks (C ABI)
 ├── proto/qpc/v1/               # 15 .proto schema files