feat(admin): super-admin user detail dashboard

Add a read-only User Detail dashboard for super admins, reachable by
clicking a user name in the admin users list.

Backend: new `admin` module aggregating existing domain services
(no new entities). ADMIN-only endpoints under /api/v1/admin:
overview (profile, account status, wallet balance, revenue, summary
counts), wallet transactions, applications (incl. deleted/docked with
restore eligibility), build/deploy errors, tickets with conversation,
and a composite activity timeline. Adds BillingService.getRevenueSummary
and guards against a wallet get-or-create race in the overview reads.

Frontend: tabbed detail page (overview/applications/activity/errors/
tickets) with lazy per-tab queries; user names in the admin list link to
it (admin only); fa/en i18n keys and response types.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

backend/src/billing/billing.service.ts

@@ -167,6 +167,35 @@ export class BillingService {
     });
   }
 
+  /**
+   * Aggregate wallet movement for a user, grouped by transaction type. Used by
+   * the admin user-detail dashboard. "revenue" is what the user actually spent
+   * on services (deductions + direct gateway payments) — i.e. platform income —
+   * as opposed to "charged" which is just money topped up into the wallet.
+   */
+  async getRevenueSummary(
+    userId: string,
+  ): Promise<{ revenue: number; charged: number; refunded: number }> {
+    const wallet = await this.getOrCreateWallet(userId);
+    const rows = await this.txRepo
+      .createQueryBuilder('tx')
+      .select('tx.type', 'type')
+      .addSelect('COALESCE(SUM(tx.amount), 0)', 'total')
+      .where('tx.walletId = :walletId', { walletId: wallet.id })
+      .groupBy('tx.type')
+      .getRawMany<{ type: TransactionType; total: string }>();
+
+    const totals = new Map(rows.map((r) => [r.type, Number(r.total)]));
+    const revenue =
+      (totals.get(TransactionType.DEDUCTION) ?? 0) +
+      (totals.get(TransactionType.GATEWAY_PAYMENT) ?? 0);
+    return {
+      revenue,
+      charged: totals.get(TransactionType.CHARGE) ?? 0,
+      refunded: totals.get(TransactionType.REFUND) ?? 0,
+    };
+  }
+
   async recordGatewayPayment(
     userId: string,
     amount: number,