fix: handle AudioBackendType::Jack in settings backend name match

The Jack backend variant was added to qbz-audio but the backend-name
match in commands_v2/settings.rs was not updated, leaving the lib crate
non-exhaustive (E0004) and uncompilable on this branch. Add the missing
arm and sync Cargo.lock with the jack/jack-sys deps. Pre-existing breakage
unrelated to qconnect; fixed here only to unblock the build and tests.

cc

src-tauri/Cargo.lock

@@ -3131,6 +3131,33 @@ version = "1.0.17"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "92ecc6618181def0457392ccd0ee51198e065e016d1d527a7ac1b6dc7c1f09d2"
 
+[[package]]
+name = "jack"
+version = "0.13.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "f7811b07bcac5dafabf814ab52c4b0ca9b7948aa1e279f572f03aa6544d47d27"
+dependencies = [
+ "bitflags 2.11.0",
+ "jack-sys",
+ "lazy_static",
+ "libc",
+ "log",
+]
+
+[[package]]
+name = "jack-sys"
+version = "0.5.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "6013b7619b95a22b576dfb43296faa4ecbe40abbdb97dfd22ead520775fc86ab"
+dependencies = [
+ "bitflags 1.3.2",
+ "lazy_static",
+ "libc",
+ "libloading 0.7.4",
+ "log",
+ "pkg-config",
+]
+
 [[package]]
 name = "javascriptcore-rs"
 version = "1.1.2"
@@ -5024,9 +5051,11 @@ dependencies = [
  "coreaudio-rs",
  "dirs 6.0.0",
  "ebur128",
+ "jack",
  "log",
  "objc2-core-audio",
  "qbz-models",
+ "ringbuf",
  "rodio",
  "rusqlite",
  "rustfft",
@@ -5365,6 +5394,7 @@ dependencies = [
 name = "qconnect-core"
 version = "0.1.0"
 dependencies = [
+ "qbz-models",
  "serde",
  "thiserror 2.0.18",
 ]
@@ -5885,6 +5915,17 @@ dependencies = [
  "windows-sys 0.52.0",
 ]
 
+[[package]]
+name = "ringbuf"
+version = "0.4.8"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "fe47b720588c8702e34b5979cb3271a8b1842c7cb6f57408efa70c779363488c"
+dependencies = [
+ "crossbeam-utils",
+ "portable-atomic",
+ "portable-atomic-util",
+]
+
 [[package]]
 name = "rodio"
 version = "0.22.2"

src-tauri/src/commands_v2/settings.rs

@@ -247,6 +247,7 @@ pub fn v2_get_available_backends() -> Result<Vec<BackendInfo>, String> {
                 AudioBackendType::Alsa => "ALSA Direct",
                 AudioBackendType::Pulse => "PulseAudio",
                 AudioBackendType::SystemDefault => "System",
+                AudioBackendType::Jack => "JACK",
             };
 
             BackendInfo {