fix(session): persist the idle inhibitor across shell restarts

quickshell/Common/SessionData.qml

@@ -34,6 +34,7 @@ Singleton {
     property bool isLightMode: false
     property bool doNotDisturb: false
     property real doNotDisturbUntil: 0
+    property bool idleInhibited: false
     property string terminalOverride: ""
     property bool isSwitchingMode: false
     property bool suppressOSD: true
@@ -626,6 +627,14 @@ Singleton {
         saveSettings();
     }
 
+    function setIdleInhibited(enabled) {
+        const next = !!enabled;
+        if (idleInhibited === next)
+            return;
+        idleInhibited = next;
+        saveSettings();
+    }
+
     function setDoNotDisturbUntilTimestamp(timestampMs) {
         const target = Number(timestampMs) || 0;
         if (target <= Date.now()) {

quickshell/Common/settings/SessionSpec.js

@@ -4,6 +4,7 @@ var SPEC = {
     isLightMode: { def: false },
     doNotDisturb: { def: false },
     doNotDisturbUntil: { def: 0 },
+    idleInhibited: { def: false },
     terminalOverride: { def: "" },
 
     wallpaperPath: { def: "" },

quickshell/Services/SessionService.qml

@@ -488,17 +488,42 @@ Singleton {
     // * Idle Inhibitor
     signal inhibitorChanged
 
+    // The inhibitor is a state the user turns on explicitly, so it is persisted in the session
+    // like the other Control Center toggles (doNotDisturb, nightModeEnabled, ...). Without this
+    // it lived only in memory and every shell restart silently cleared it.
+    //
+    // Both entry points are needed because the two singletons are lazily created and the order is
+    // not fixed: onLoaded covers "service first, session file read later", the restore below
+    // covers "session already loaded by the time the service is instantiated". enableIdleInhibit
+    // is idempotent, so whichever runs second does nothing.
+    function _restoreIdleInhibit() {
+        if (SessionData.idleInhibited && !idleInhibited)
+            enableIdleInhibit();
+    }
+
+    Connections {
+        target: SessionData
+
+        function onLoaded() {
+            root._restoreIdleInhibit();
+        }
+    }
+
+    Component.onCompleted: _restoreIdleInhibit()
+
     function enableIdleInhibit() {
         if (idleInhibited)
             return;
         idleInhibited = true;
+        SessionData.setIdleInhibited(true);
         inhibitorChanged();
     }
 
     function disableIdleInhibit() {
         if (!idleInhibited)
             return;
         idleInhibited = false;
+        SessionData.setIdleInhibited(false);
         inhibitorChanged();
     }