refactor(SysUpdate): Explicit Run on Startup option in settings

- Relocated DMS System Updater to System Setting section
- Removed forced auto refresh upon update & widget loading

quickshell/Modules/DankBar/Popouts/SystemUpdatePopout.qml

@@ -75,16 +75,6 @@ DankPopout {
         close();
     }
 
-    onShouldBeVisibleChanged: {
-        if (!shouldBeVisible) {
-            return;
-        }
-        const stale = !SystemUpdateService.lastCheckUnix || (Date.now() / 1000 - SystemUpdateService.lastCheckUnix) > 300;
-        if (stale && !SystemUpdateService.isChecking && !SystemUpdateService.isUpgrading) {
-            SystemUpdateService.checkForUpdates();
-        }
-    }
-
     content: Component {
         Rectangle {
             id: updaterPanel

quickshell/Modules/Settings/SystemUpdaterTab.qml

@@ -93,6 +93,13 @@ Item {
                     }
                 }
 
+                SettingsToggleRow {
+                    text: I18n.tr("Check on startup")
+                    description: I18n.tr("When enabled, checks updates on startup. When disabled, only the interval above or a manual refresh runs a check.")
+                    checked: SettingsData.updaterCheckOnStart
+                    onToggled: checked => SettingsData.set("updaterCheckOnStart", checked)
+                }
+
                 SettingsToggleRow {
                     text: I18n.tr("Include Flatpak updates")
                     description: I18n.tr("Apply Flatpak updates alongside system updates when running 'Update All'.")