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,

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

@@ -8,7 +8,7 @@ import { t, tf } from '@nexumi/shared';
 import type { SlashCommand } from '../../types.js';
 import { requirePermission } from '../../permissions.js';
 import { assertModerableMember } from '../../hierarchy.js';
-import { applyWarnEscalation, createCase, createWarning } from './service.js';
+import { applyWarnEscalation, createCase, createWarning, notifyModerationTargetDm } from './service.js';
 import { parseDuration, parseTimeoutDuration, tryParseDuration } from './duration.js';
 import { getGuildLocale } from '../../i18n.js';
 import { promptDestructiveConfirmation } from './confirmations.js';
@@ -133,6 +133,13 @@ const kickCommand: SlashCommand = {
     const reason = reasonFrom(interaction, locale);
     const hierarchy = await assertModerableMember(interaction, user.id, locale, 'kick');
     if (!hierarchy.ok || !hierarchy.member) return;
+    await notifyModerationTargetDm({
+      user,
+      guildName: interaction.guild!.name,
+      reason,
+      locale,
+      action: 'kick'
+    });
     await hierarchy.member.kick(reason);
     const modCase = await createCase(context, {
       guildId: interaction.guildId!,

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

@@ -64,6 +64,37 @@ async function notifyWarnedUser(params: {
   }
 }
 
+export async function notifyModerationTargetDm(params: {
+  user: User;
+  guildName: string;
+  reason: string;
+  locale: Locale;
+  action: 'ban' | 'kick';
+  duration?: string | null;
+}): Promise<void> {
+  const reason = params.reason || t(params.locale, 'moderation.reason.none');
+  const key =
+    params.action === 'kick'
+      ? 'moderation.kick.dm'
+      : params.duration
+        ? 'moderation.ban.dm.temporary'
+        : 'moderation.ban.dm';
+  try {
+    await params.user.send(
+      tf(params.locale, key, {
+        guild: params.guildName,
+        reason,
+        ...(params.duration ? { duration: params.duration } : {})
+      })
+    );
+  } catch (error) {
+    logger.warn(
+      { error, userId: params.user.id, action: params.action },
+      'Failed to DM moderation target'
+    );
+  }
+}
+
 export async function createWarning(
   context: BotContext,
   input: CreateWarningInput
@@ -298,6 +329,13 @@ export async function applyWarnEscalation(
         String(warningCount)
       );
     }
+    await notifyModerationTargetDm({
+      user: member.user,
+      guildName: interaction.guild.name,
+      reason,
+      locale,
+      action: 'kick'
+    });
     await member.kick(reason);
     await createCase(context, {
       guildId,
@@ -318,6 +356,13 @@ export async function applyWarnEscalation(
       String(warningCount)
     );
   }
+  await notifyModerationTargetDm({
+    user: member.user,
+    guildName: interaction.guild.name,
+    reason,
+    locale,
+    action: 'ban'
+  });
   await interaction.guild.members.ban(userId, { reason });
   await createCase(context, {
     guildId,