refactor: switch to tsclientlib for TeamSpeak protocol

- Replace custom Session/SessionHandle with tsclientlib SyncConnection
- SyncConnection runs in background task, forwards events via mpsc
- iced subscription reads events from mpsc channel
- SendChannelMessage sends via SyncConnectionHandle::with_connection
- Disconnect sends DisconnectOptions via handle
- State refresh reads data::Connection (clients, channels, server)
- Keep tscore QueryClient for ServerQuery panel
- Add tsclientlib as path dependency (from refercence/)
- CI checkout with submodules: recursive for tsdeclarations
- 69 tests passing, clippy clean

.github/workflows/ci.yml

@@ -31,6 +31,8 @@ jobs:
 
     steps:
     - uses: actions/checkout@v4
+      with:
+        submodules: recursive
 
     - name: Install Rust
       uses: dtolnay/rust-toolchain@stable
@@ -94,6 +96,8 @@ jobs:
 
     steps:
     - uses: actions/checkout@v4
+      with:
+        submodules: recursive
 
     - name: Install Rust
       uses: dtolnay/rust-toolchain@stable