Implement leave announcement for banned members and enhance moderation notifications

- Added a `leaveAnnounceBan` field to the `WelcomeConfig` model, allowing for optional announcements in the leave channel when a member is banned.
- Updated the leave handling logic to check for bans and send a notice in the leave channel if the `leaveAnnounceBan` toggle is enabled.
- Enhanced moderation actions (kick and ban) to notify the affected user via DM with the reason for the action.
- Introduced a new `notifyModerationTargetDm` function to streamline DM notifications for moderation actions.
- Updated the WebUI to include a toggle for the `leaveAnnounceBan` feature, improving user configurability.
- Improved localization for new messages related to moderation notifications and leave announcements in both English and German.
- Documented changes in phase tracking to reflect the new leave announcement feature and moderation notification enhancements.

apps/bot/src/modules/moderation/actions.ts

@@ -2,7 +2,7 @@ import { TextChannel, type ButtonInteraction } from 'discord.js';
 import { type Locale, t, tf } from '@nexumi/shared';
 import type { BotContext } from '../../types.js';
 import { assertBannableForConfirm } from '../../hierarchy.js';
-import { createCase, scheduleTempBanExpire } from './service.js';
+import { createCase, notifyModerationTargetDm, scheduleTempBanExpire } from './service.js';
 import { tryParseDuration } from './duration.js';
 
 type BanPayload = {
@@ -55,6 +55,18 @@ export async function executeBan(
 
   await interaction.deferUpdate();
 
+  const targetUser = await context.client.users.fetch(payload.userId).catch(() => null);
+  if (targetUser) {
+    await notifyModerationTargetDm({
+      user: targetUser,
+      guildName: guild.name,
+      reason: payload.reason,
+      locale,
+      action: 'ban',
+      duration: payload.duration
+    });
+  }
+
   await guild.members.ban(payload.userId, { reason: payload.reason });
   const modCase = await createCase(context, {
     guildId: guild.id,