feat: add daily digest email notification module

- New DailyDigestModule with scheduled summary email for open dashboard items
- Extract StatsService from StatsController for reuse in digest
- Add DailyDigestEnabled, UserEmail, UserPreferredUsername to UserSettings entity
- Sync email/username from OIDC token on each get/update call
- Add dailyDigestEnabled to UserSettingsDto and update API
- Notifications tab in UserSettingsPage with enable toggle and "Jetzt senden" button

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

paperless-backend/src/user-settings/user-settings.service.ts

@@ -19,6 +19,7 @@ export interface UserSettingsDto {
   mailSignatureHtml: string | null;
   defaultLabelTemplateId: number | null;
   emailRecipientHistory: string[] | null;
+  dailyDigestEnabled: boolean;
 }
 
 @Injectable()
@@ -64,8 +65,16 @@ export class UserSettingsService {
     return Buffer.concat([decipher.update(encrypted), decipher.final()]).toString('utf8');
   }
 
-  async getSettings(userId: string): Promise<UserSettingsDto> {
-    const entity = await this.repo.findOne({ where: { UserId: userId } });
+  async getSettings(userId: string, email?: string, preferredUsername?: string): Promise<UserSettingsDto> {
+    let entity = await this.repo.findOne({ where: { UserId: userId } });
+    if (email || preferredUsername) {
+      if (!entity) {
+        entity = this.repo.create({ UserId: userId });
+      }
+      if (email) entity.UserEmail = email;
+      if (preferredUsername) entity.UserPreferredUsername = preferredUsername;
+      await this.repo.save(entity);
+    }
     return this.toDto(entity);
   }
 
@@ -82,7 +91,10 @@ export class UserSettingsService {
       mailSignatureHtml?: string | null;
       defaultLabelTemplateId?: number | null;
       emailRecipientHistory?: string[] | null;
+      dailyDigestEnabled?: boolean;
     },
+    email?: string,
+    preferredUsername?: string,
   ): Promise<UserSettingsDto> {
     let entity = await this.repo.findOne({ where: { UserId: userId } });
     if (!entity) {
@@ -101,6 +113,9 @@ export class UserSettingsService {
     if (data.mailSignatureHtml !== undefined) entity.MailSignatureHtml = data.mailSignatureHtml;
     if (data.defaultLabelTemplateId !== undefined) entity.DefaultLabelTemplateId = data.defaultLabelTemplateId;
     if (data.emailRecipientHistory !== undefined) entity.EmailRecipientHistory = data.emailRecipientHistory;
+    if (data.dailyDigestEnabled !== undefined) entity.DailyDigestEnabled = data.dailyDigestEnabled;
+    if (email) entity.UserEmail = email;
+    if (preferredUsername) entity.UserPreferredUsername = preferredUsername;
 
     await this.repo.save(entity);
     return this.toDto(entity);
@@ -144,6 +159,12 @@ export class UserSettingsService {
     };
   }
 
+  async findAllDigestSubscribers(): Promise<UserSettings[]> {
+    return this.repo.find({
+      where: { DailyDigestEnabled: true },
+    }).then(rows => rows.filter(r => !!r.UserEmail));
+  }
+
   async getAvailableSenders(userId: string): Promise<{ id: string; label: string }[]> {
     const defaultEmail = this.configService.get<string>('SMTP_FROM', 'paperless@localhost');
     const defaultName = this.configService.get<string>('SMTP_FROM_NAME', '');
@@ -172,6 +193,7 @@ export class UserSettingsService {
       mailSignatureHtml: entity?.MailSignatureHtml ?? null,
       defaultLabelTemplateId: entity?.DefaultLabelTemplateId ?? null,
       emailRecipientHistory: entity?.EmailRecipientHistory ?? null,
+      dailyDigestEnabled: entity?.DailyDigestEnabled ?? false,
     };
   }
 }