[feat](trx-client): add local cpal audio bridge for WSJT-X

Add configurable bidirectional local audio bridge (RX playback + TX capture) using cpal/opus for virtual-device routing on Linux/macOS, and document bridge settings.

Also expand rigctl frontend command compatibility aliases for hamlib/WSJT-X clients.

Co-authored-by: Codex <codex@openai.com>
Signed-off-by: Stanislaw Grams <stanislawgrams@gmail.com>

src/trx-client/Cargo.toml

@@ -16,6 +16,8 @@ tracing = { workspace = true }
 clap = { workspace = true, features = ["derive"] }
 dirs = "6"
 bytes = "1"
+cpal = "0.15"
+opus = "0.3"
 trx-app = { path = "../trx-app" }
 trx-core = { path = "../trx-core" }
 trx-protocol = { path = "../trx-protocol" }