fix(build): gate macOS-unreachable imports to cfg(target_os = "linux")

The v1.2.5 tag push flagged three macOS-only compile errors on the
release-macos workflow (Linux, aarch64 Linux, flatpak still building
successfully). All three are Linux-only symbols pulled unconditionally
into files that are compiled on every target:

  * src-tauri/src/tray.rs: imports PathBuf inside the
    `cfg(not(target_os = "linux"))` branch without `use std::path::PathBuf`.
    Add the import under the matching cfg so macOS / Windows see it.

  * src-tauri/src/commands_v2/playback.rs: `cached_audio_incompatible_with_hw`
    is defined only on Linux (ALSA). Callsites are already
    `cfg(target_os = "linux")`, but the shared `use super::{...}` block
    was not. Move that one symbol out into a Linux-only import.

  * src-tauri/src/commands_v2/legacy_compat.rs: same story with
    `v2_prepare_notification_icon_bytes` — only the Linux notification
    path calls it, but the import was unconditional.

No runtime behaviour change; this only unblocks the release-macos
(and any future Apple-target) workflow so it can build.

cc

src-tauri/src/commands_v2/legacy_compat.rs

@@ -29,8 +29,13 @@ use crate::AppState;
 
 use super::{
     download_audio, v2_cache_notification_artwork, v2_format_notification_quality,
-    v2_prepare_notification_icon_bytes, v2_teardown_type_alias_state,
+    v2_teardown_type_alias_state,
 };
+// Linux-only: turns an artwork PNG into the raw bytes Ayatana notifications
+// expect. Only called inside the `cfg(target_os = "linux")` arm below, so the
+// import must match.
+#[cfg(target_os = "linux")]
+use super::v2_prepare_notification_icon_bytes;
 
 #[tauri::command]
 pub async fn v2_show_track_notification(

src-tauri/src/commands_v2/playback.rs

@@ -14,10 +14,15 @@ use crate::runtime::{CommandRequirement, RuntimeError, RuntimeManagerState};
 use crate::AppState;
 
 use super::{
-    cached_audio_incompatible_with_hw, cached_quality_below_requested, download_with_backoff,
-    limit_quality_for_device, parse_quality, try_cmaf_full_download, try_cmaf_streaming_setup,
-    v2_cmaf_stream, v2_download_and_stream, v2_get_stream_info, v2_library_get_tracks_by_ids,
+    cached_quality_below_requested, download_with_backoff, limit_quality_for_device,
+    parse_quality, try_cmaf_full_download, try_cmaf_streaming_setup, v2_cmaf_stream,
+    v2_download_and_stream, v2_get_stream_info, v2_library_get_tracks_by_ids,
 };
+// Linux-only: ALSA hardware capability check. The callsites that use it are
+// already gated on `cfg(target_os = "linux")`, so the import has to match or
+// macOS fails with "unresolved import".
+#[cfg(target_os = "linux")]
+use super::cached_audio_incompatible_with_hw;
 
 // ==================== Prefetch (V2) ====================
 

src-tauri/src/tray.rs

@@ -11,6 +11,8 @@ use crate::tray_linux_ksni;
 #[cfg(not(target_os = "linux"))]
 use image::GenericImageView;
 #[cfg(not(target_os = "linux"))]
+use std::path::PathBuf;
+#[cfg(not(target_os = "linux"))]
 use tauri::{
     image::Image,
     menu::{Menu, MenuItem, PredefinedMenuItem},