feat(qbz-audio): add device-reservation module skeleton with parsers

Adds the new module that will host the org.freedesktop.ReserveDevice1
D-Bus client. This commit only ships the public surface, the parser
helpers (hw:N -> Audio<N> bus name, hw:CARD=name resolution) and unit
tests for them. acquire() currently returns a degraded guard; D-Bus
implementation lands in the next commit.

cc

crates/qbz-audio/Cargo.toml

@@ -41,6 +41,10 @@ dirs = "6"
 alsa = "0.10"
 # alsa-sys: direct FFI for snd_lib_error_set_handler (custom error routing)
 alsa-sys = "0.3"
+# zbus for org.freedesktop.ReserveDevice1 D-Bus client (device reservation).
+# Pinned to v4 to share the transitive copy already pulled in by
+# secret-service/souvlaki and avoid duplicate zbus compiles.
+zbus = { version = "4", default-features = false, features = ["tokio"] }
 
 [target.'cfg(target_os = "macos")'.dependencies]
 # CoreAudio for device probing, sample rate switching, and (future) hog mode / exclusive mode