feat: add admin log viewer, log retention cleanup, and manual job triggers

Global admins couldn't see the app's event log (no read endpoint or UI
existed for it) and had no way to clean up old entries or re-run a
scheduled job without touching the database or server directly.

Backend:
- LoggingService.findLogs() + admin-only LogsController (GET
  admin/logs) with level/event/date-range/search filtering and
  pagination, mirroring AdminUsersService.findPlayers().
- LogRetentionScheduler deletes log entries older than
  LOG_RETENTION_DAYS (default 365, via app.config.ts), following the
  existing @Cron scheduler pattern.
- Admin-only POST admin/run endpoints on CashboxExportController and
  RecurringTransactionsController that invoke the existing schedulers'
  public run methods on demand - both are safe to re-run since their
  "due" queries advance nextRunDate only after a successful run.

Frontend:
- New /logs page (global-admin gated, same pattern as /users): AG-Grid
  infinite-scroll table with level/event/date-range/search filters,
  plus buttons to trigger the two jobs now and see the result land in
  the grid immediately.
- LogsApi, and triggerRunNow() added to the existing CashboxExportApi
  and RecurringTransactionApi.
- Discoverability link from /users to /logs.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

myteamwallet_backend/src/database/logging/log-retention.scheduler.ts

@@ -0,0 +1,32 @@
+import { Injectable } from '@nestjs/common';
+import { Cron, CronExpression } from '@nestjs/schedule';
+import { ConfigService } from '@nestjs/config';
+import { InjectRepository } from '@nestjs/typeorm';
+import { LessThan, Repository } from 'typeorm';
+import { LogEntry } from './entities/log-entry.entity';
+import { LoggingService } from './logging.service';
+
+@Injectable()
+export class LogRetentionScheduler {
+  constructor(
+    @InjectRepository(LogEntry)
+    private readonly repository: Repository<LogEntry>,
+    private readonly configService: ConfigService,
+    private readonly logger: LoggingService,
+  ) {}
+
+  @Cron(CronExpression.EVERY_DAY_AT_4AM)
+  async cleanupOldLogs(): Promise<void> {
+    const retentionDays = this.configService.get<number>('app.logRetentionDays');
+    const cutoff = new Date();
+    cutoff.setUTCDate(cutoff.getUTCDate() - retentionDays);
+
+    const result = await this.repository.delete({ createdAt: LessThan(cutoff) });
+
+    await this.logger.info({
+      event: 'log_retention_cleanup_run',
+      details: `deletedCount=${result.affected ?? 0} retentionDays=${retentionDays}`,
+      userId: -1,
+    });
+  }
+}