Implement maintenance mode and presence updates in bot and WebUI

- Added maintenance mode functionality in the bot, allowing for a custom message and DND status when enabled.
- Updated the OwnerPresencePage to include read-only access for VIEWER roles, with save permissions restricted to ADMIN roles.
- Enhanced the PresenceForm component to support immediate application of changes and added a confirmation for maintenance mode activation.
- Introduced localization updates for presence-related messages in both English and German, improving user guidance.
- Implemented a presence refresh queue to handle updates efficiently after configuration changes.

apps/bot/src/presence.ts

@@ -120,6 +120,23 @@ export async function readPresenceConfig(context: BotContext): Promise<BotPresen
 
 export async function applyBotPresence(context: BotContext): Promise<void> {
   const config = await readPresenceConfig(context);
+
+  if (config.maintenanceMode) {
+    const text =
+      config.maintenanceMessage?.trim() ||
+      'Maintenance mode — please try again later.';
+    await context.client.user?.setPresence({
+      status: 'dnd',
+      activities: [
+        {
+          name: text.slice(0, 128),
+          type: ActivityType.Watching
+        }
+      ]
+    });
+    return;
+  }
+
   const messages =
     config.rotatingMessages.length > 0 ? config.rotatingMessages : [config.activityText];
   const index = Math.floor(Date.now() / 60_000) % messages.length;