feat(notify): per-sound notification toggles (W6)

Add a per-event enable checkbox next to each chime in Settings so a user
can silence individual sounds (e.g. keep 'message'/peer-join but drop
reconnect chimes) while the master 'Enable sound notifications' toggle
stays as the global kill-switch.

The gate lives in one place at the play() seam: a pure should_play(master,
sound) AND that's unit-tested, fed by a per-sound AtomicBool array in
notify keyed by a stable Sound::index/ALL. Flags persist as 8 sound_*_enabled
bools in AppConfig (default true, so upgrades are silent-change-free) with
sound_enabled/set_sound_enabled accessors centralizing the field mapping.
The per-sound checkbox greys out (drops on_toggle) while the master is off.

+3 notify unit tests (should_play truth table, index bijection, flag
set/query independence) + extended config backward-compat test. 230 lib
tests green, clippy clean.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

src/config.rs

@@ -1,3 +1,4 @@
+use crate::notify::Sound;
 use crate::theme::AppTheme;
 use serde::{Deserialize, Serialize};
 use std::fs;
@@ -198,6 +199,26 @@ pub struct AppConfig {
     pub custom_sound_mic_toggle: Option<String>,
     #[serde(default)]
     pub custom_sound_reconnect_failed: Option<String>,
+    /// Per-sound enable flags (W6). The master `notifications_enabled` toggle
+    /// gates ALL chimes; these let the user silence individual events while the
+    /// master stays on. A chime plays only if the master AND its flag are true.
+    /// Default true so behaviour is unchanged until a user opts a sound out.
+    #[serde(default = "default_true")]
+    pub sound_self_join_enabled: bool,
+    #[serde(default = "default_true")]
+    pub sound_peer_join_enabled: bool,
+    #[serde(default = "default_true")]
+    pub sound_peer_leave_enabled: bool,
+    #[serde(default = "default_true")]
+    pub sound_reconnect_attempt_enabled: bool,
+    #[serde(default = "default_true")]
+    pub sound_reconnected_enabled: bool,
+    #[serde(default = "default_true")]
+    pub sound_self_leave_enabled: bool,
+    #[serde(default = "default_true")]
+    pub sound_mic_toggle_enabled: bool,
+    #[serde(default = "default_true")]
+    pub sound_reconnect_failed_enabled: bool,
     /// Optional override for the `pixelpass` binary location (screen share).
     /// Empty / unset = look it up on `$PATH`. Hand-editable; no Settings UI yet.
     #[serde(default)]
@@ -246,6 +267,14 @@ impl Default for AppConfig {
             custom_sound_self_leave: None,
             custom_sound_mic_toggle: None,
             custom_sound_reconnect_failed: None,
+            sound_self_join_enabled: true,
+            sound_peer_join_enabled: true,
+            sound_peer_leave_enabled: true,
+            sound_reconnect_attempt_enabled: true,
+            sound_reconnected_enabled: true,
+            sound_self_leave_enabled: true,
+            sound_mic_toggle_enabled: true,
+            sound_reconnect_failed_enabled: true,
             pixelpass_path: None,
             window_width: default_window_width(),
             window_height: default_window_height(),
@@ -256,6 +285,35 @@ impl Default for AppConfig {
 }
 
 impl AppConfig {
+    /// Whether the chime for `sound` is enabled (its own per-sound flag; does
+    /// NOT factor in the master `notifications_enabled` toggle — see `notify`).
+    pub fn sound_enabled(&self, sound: Sound) -> bool {
+        match sound {
+            Sound::SelfJoin => self.sound_self_join_enabled,
+            Sound::PeerJoin => self.sound_peer_join_enabled,
+            Sound::PeerLeave => self.sound_peer_leave_enabled,
+            Sound::ReconnectAttempt => self.sound_reconnect_attempt_enabled,
+            Sound::Reconnected => self.sound_reconnected_enabled,
+            Sound::SelfLeave => self.sound_self_leave_enabled,
+            Sound::MicToggle => self.sound_mic_toggle_enabled,
+            Sound::ReconnectFailed => self.sound_reconnect_failed_enabled,
+        }
+    }
+
+    /// Set the per-sound enable flag for `sound`.
+    pub fn set_sound_enabled(&mut self, sound: Sound, enabled: bool) {
+        match sound {
+            Sound::SelfJoin => self.sound_self_join_enabled = enabled,
+            Sound::PeerJoin => self.sound_peer_join_enabled = enabled,
+            Sound::PeerLeave => self.sound_peer_leave_enabled = enabled,
+            Sound::ReconnectAttempt => self.sound_reconnect_attempt_enabled = enabled,
+            Sound::Reconnected => self.sound_reconnected_enabled = enabled,
+            Sound::SelfLeave => self.sound_self_leave_enabled = enabled,
+            Sound::MicToggle => self.sound_mic_toggle_enabled = enabled,
+            Sound::ReconnectFailed => self.sound_reconnect_failed_enabled = enabled,
+        }
+    }
+
     fn config_path() -> Option<PathBuf> {
         dirs::config_dir().map(|mut p| {
             p.push("peerspeak");
@@ -325,6 +383,16 @@ mod tests {
         assert!(deserialized.custom_sound_self_leave.is_none());
         assert!(deserialized.custom_sound_mic_toggle.is_none());
         assert!(deserialized.custom_sound_reconnect_failed.is_none());
+        // Configs predating the per-sound flags (W6) enable every chime, so an
+        // upgrade is silent-change-free.
+        for sound in Sound::ALL {
+            assert!(deserialized.sound_enabled(sound), "{sound:?} should default on");
+        }
+        // The accessor and mutator agree round-trip.
+        let mut cfg = AppConfig::default();
+        cfg.set_sound_enabled(Sound::PeerJoin, false);
+        assert!(!cfg.sound_enabled(Sound::PeerJoin));
+        assert!(cfg.sound_enabled(Sound::SelfJoin));
         // Configs predating the remembered window size load the default size.
         assert_eq!(deserialized.window_width, 900.0);
         assert_eq!(deserialized.window_height, 760.0);