feat(core,gui): tray states and menu

The tray icon follows the drive's phase (synced, syncing, paused,
offline, needs attention) and reports NeedsAttention while changes keep
failing. The menu gains an issues item that opens the Sync page, Sign In
when signed out, Hide Tray Icon (persisted as tray_hidden) and Stop
Proton Drive, which pdfs-app confirms via --confirm-stop. A second
pdfs-app launch raises the running window.

crates/pdfs-gui/src/app/pages/status.rs

@@ -46,6 +46,8 @@ pub(crate) struct StatusState {
     pub(crate) mountpoint_row: adw::ActionRow,
     /// "Proton purple accent" toggle. Guarded by [`Self::settings_suppress`].
     pub(crate) accent_row: adw::SwitchRow,
+    /// "Show tray icon" toggle. Guarded by [`Self::settings_suppress`].
+    pub(crate) tray_row: adw::SwitchRow,
     /// Set while a settings widget is being populated programmatically, so its
     /// change handler skips the IPC/systemd side effect.
     pub(crate) settings_suppress: Cell<bool>,
@@ -135,6 +137,7 @@ pub(crate) struct MainWidgets {
     pub(crate) mountpoint_row: adw::ActionRow,
     pub(crate) mountpoint_button: gtk4::Button,
     pub(crate) accent_row: adw::SwitchRow,
+    pub(crate) tray_row: adw::SwitchRow,
 }
 
 /// Build the two surfaces that replaced the old Settings page:
@@ -193,6 +196,11 @@ pub(crate) fn build_main_page() -> MainWidgets {
         .subtitle("Use the Proton brand color instead of the system accent color")
         .build();
     appearance_group.add(&accent_row);
+    let tray_row = adw::SwitchRow::builder()
+        .title("Show tray icon")
+        .subtitle("Sync status and quick actions in the panel")
+        .build();
+    appearance_group.add(&tray_row);
 
     let general = adw::PreferencesPage::builder()
         .title("General")
@@ -362,6 +370,7 @@ pub(crate) fn build_main_page() -> MainWidgets {
         mountpoint_row,
         mountpoint_button,
         accent_row,
+        tray_row,
     }
 }
 
@@ -420,6 +429,7 @@ pub(crate) fn wire_settings(
     ui.status
         .accent_row
         .set_active(config.proton_accent.unwrap_or(false));
+    ui.status.tray_row.set_active(!config.tray_hidden);
     ui.status.settings_suppress.set(false);
 
     // Cache budget: a user edit applies the new soft cap on the daemon (which
@@ -534,6 +544,27 @@ pub(crate) fn wire_settings(
             toast_error(&ui_accent, "Couldn't save the accent color", &e.to_string());
         }
     });
+
+    // Tray icon: the tray reads the same flag at start, so hiding it here also
+    // keeps the login autostart from bringing it back.
+    let ui_tray = ui.clone();
+    ui.status.tray_row.connect_active_notify(move |row| {
+        if ui_tray.status.settings_suppress.get() {
+            return;
+        }
+        let show = row.is_active();
+        let mut config = ui_tray.dirs.load_config();
+        config.tray_hidden = !show;
+        if let Err(e) = ui_tray.dirs.save_config(&config) {
+            toast_error(&ui_tray, "Couldn't save the tray setting", &e.to_string());
+            return;
+        }
+        if show {
+            spawn_tray();
+        } else {
+            pdfs_core::tray::quit(&ui_tray.dirs);
+        }
+    });
 }
 
 /// Run a settings control-socket round-trip (budget / purge) on a worker thread,