fix(audio): skip the Linux stack probes on Windows

A spawn of an image that does not exist fails before a process is created, so
pactl, pw-dump and systemctl were harmless on Windows. sh is not: it exists
wherever Git for Windows is installed, so the five sh -c probes in
audio_stack_health really ran and flashed five console windows past a
GUI-subsystem binary that owns no console.

Scoped to windows / not(windows), NOT to linux / not(linux). macOS and the
BSDs can have a real pactl or pw-dump from Homebrew or ports, and answering
false for them would take away an answer they can give.

qbz-theme needed nothing: its dispatch is by XDG_CURRENT_DESKTOP, so Windows
resolves DesktopEnvironment::Unknown, whose arm returns Err without calling
any desktop probe.

cc

crates/qbz-audio/src/dac_probe.rs

@@ -11,6 +11,8 @@
 //! bit-perfect / sample-rate-passthrough path is untouched.
 
 use serde::{Deserialize, Serialize};
+// Every target but Windows still runs `pw-dump`.
+#[cfg(not(windows))]
 use std::process::Command;
 
 /// The DAC's live, negotiated hardware state — what the card is REALLY clocked
@@ -94,6 +96,18 @@ pub fn parse_alsa_card_for_node(json: &str, node_name: &str) -> Option<u32> {
 }
 
 /// Resolve the ALSA card number for a sink node by running `pw-dump`.
+///
+/// W14, Windows only: `pw-dump` does not exist there, so the spawn already
+/// failed into this same None. Scoped to Windows rather than `not(linux)` --
+/// a macOS or BSD box can have a real `pw-dump`, and this function is not the
+/// place to decide it may not speak.
+#[cfg(windows)]
+fn alsa_card_for_node(_node_name: &str) -> Option<u32> {
+    None
+}
+
+/// Resolve the ALSA card number for a sink node by running `pw-dump`.
+#[cfg(not(windows))]
 fn alsa_card_for_node(node_name: &str) -> Option<u32> {
     let output = Command::new("pw-dump").output().ok()?;
     if !output.status.success() {

crates/qbz-audio/src/health.rs

@@ -5,6 +5,8 @@
 //! the check step can show the right `apt`/`dnf`/`pacman` remediation. None of
 //! this opens a stream — purely diagnostic.
 
+// Every target but Windows still probes; see `audio_stack_health`.
+#[cfg(not(windows))]
 use std::process::Command;
 
 /// Result of the audio-stack probes. All best-effort; a failed probe reads as
@@ -32,7 +34,8 @@ impl AudioStackHealth {
     }
 }
 
-/// True if `sh -c "<probe>"` exits 0.
+/// True if `sh -c "<probe>"` exits 0. Windows never probes; see below.
+#[cfg(not(windows))]
 fn sh_ok(probe: &str) -> bool {
     Command::new("sh")
         .arg("-c")
@@ -44,6 +47,31 @@ fn sh_ok(probe: &str) -> bool {
 
 /// Run the audio-stack probes. Linux-only meaningfully; elsewhere everything
 /// reads false except where trivially true.
+///
+/// W14: on WINDOWS ONLY the answer is all-false, returned WITHOUT running the
+/// probes. `systemctl`, `pactl` and `pw-dump` do not exist there (a spawn of a
+/// missing image fails before a process is made, which is harmless), but `sh`
+/// DOES exist wherever Git for Windows is installed, so the five `sh -c`
+/// probes really run and flash five console windows past a GUI-subsystem
+/// binary that owns no console.
+///
+/// Scoped to Windows, not to `not(linux)`: macOS and the BSDs can have a real
+/// `pactl`/`pw-dump` from Homebrew or ports, and answering false for them
+/// would be a lie this diff has no business telling.
+#[cfg(windows)]
+pub fn audio_stack_health() -> AudioStackHealth {
+    AudioStackHealth {
+        wireplumber_active: false,
+        has_pw_dump: false,
+        cpal_sees_pipewire: false,
+        has_pactl: false,
+        any_devices: false,
+    }
+}
+
+/// Run the audio-stack probes. Linux-only meaningfully; elsewhere everything
+/// reads false except where trivially true.
+#[cfg(not(windows))]
 pub fn audio_stack_health() -> AudioStackHealth {
     // systemd path first; fall back to a process check so non-systemd inits
     // (Gentoo/OpenRC, Void/runit) don't read as "WirePlumber down".

crates/qbz-qt/src/diagnostics_qt.rs

@@ -1163,6 +1163,16 @@ fn collect_output_sinks() -> (Option<String>, Vec<String>, Option<(String, Strin
 /// right now (vs the saved "Preferred Sample Rate"). Linux/PipeWire/Pulse only;
 /// `None` when pactl is unavailable (a Flatpak/Snap sandbox without it simply
 /// degrades to "—", same as the reference). READ-ONLY.
+/// W14, Windows only: `pactl` is a Pulse/PipeWire tool and does not exist on
+/// Windows, so the row degrades to the same "-" the missing-pactl path already
+/// produced -- without the spawn. macOS and the BSDs keep probing: a Homebrew
+/// or ports `pactl` there is real and can answer.
+#[cfg(windows)]
+fn active_sink_format() -> Option<(String, String)> {
+    None
+}
+
+#[cfg(not(windows))]
 fn active_sink_format() -> Option<(String, String)> {
     use std::process::Command;
     let default = Command::new("pactl")