feat(03-01): add requireAdminEmail middleware and getAnalyticsSummary function

- requireAdmin.ts: returns 404 (not 403) for non-admin users per locked decision
- Reads env vars inside function body to avoid Firebase Secrets timing issue
- Fails closed if neither ADMIN_EMAIL nor EMAIL_WEEKLY_RECIPIENT configured
- analyticsService.ts: adds AnalyticsSummary interface and getAnalyticsSummary()
- Uses getPostgresPool() for aggregate SQL (COUNT/AVG not supported by Supabase JS)
- Parameterized interval with $1::interval cast for PostgreSQL compatibility

backend/src/middleware/requireAdmin.ts

@@ -0,0 +1,33 @@
+import { Response, NextFunction } from 'express';
+import { FirebaseAuthenticatedRequest } from './firebaseAuth';
+import { logger } from '../utils/logger';
+
+export function requireAdminEmail(
+  req: FirebaseAuthenticatedRequest,
+  res: Response,
+  next: NextFunction
+): void {
+  // Read inside function, not at module level — Firebase Secrets not available at module load time
+  const adminEmail = process.env['ADMIN_EMAIL'] ?? process.env['EMAIL_WEEKLY_RECIPIENT'];
+
+  if (!adminEmail) {
+    logger.warn('requireAdminEmail: neither ADMIN_EMAIL nor EMAIL_WEEKLY_RECIPIENT is configured — denying all admin access');
+    res.status(404).json({ error: 'Not found' });
+    return;
+  }
+
+  const userEmail = req.user?.email;
+
+  if (!userEmail || userEmail !== adminEmail) {
+    // 404 — do not reveal admin routes exist (per locked decision)
+    logger.warn('requireAdminEmail: access denied', {
+      uid: req.user?.uid ?? 'unauthenticated',
+      email: userEmail ?? 'none',
+      path: req.path,
+    });
+    res.status(404).json({ error: 'Not found' });
+    return;
+  }
+
+  next();
+}

backend/src/services/analyticsService.ts

@@ -1,4 +1,5 @@
 import { getSupabaseServiceClient } from '../config/supabase';
+import { getPostgresPool } from '../config/supabase';
 import { logger } from '../utils/logger';
 
 // =============================================================================
@@ -86,3 +87,62 @@ export async function deleteProcessingEventsOlderThan(days: number): Promise<num
 
   return data ? data.length : 0;
 }
+
+// =============================================================================
+// AnalyticsSummary — aggregate query for admin API
+// =============================================================================
+
+export interface AnalyticsSummary {
+  range: string;
+  totalUploads: number;
+  succeeded: number;
+  failed: number;
+  successRate: number;
+  avgProcessingMs: number | null;
+  generatedAt: string;
+}
+
+function parseRange(range: string): string {
+  if (/^\d+h$/.test(range)) return range.replace('h', ' hours');
+  if (/^\d+d$/.test(range)) return range.replace('d', ' days');
+  return '24 hours'; // fallback default
+}
+
+/**
+ * Returns a processing summary aggregate for the given time range.
+ * Uses getPostgresPool() for aggregate SQL — Supabase JS client does not support COUNT/AVG.
+ */
+export async function getAnalyticsSummary(range: string = '24h'): Promise<AnalyticsSummary> {
+  const interval = parseRange(range);
+  const pool = getPostgresPool();
+
+  const { rows } = await pool.query<{
+    total_uploads: string;
+    succeeded: string;
+    failed: string;
+    avg_processing_ms: string | null;
+  }>(`
+    SELECT
+      COUNT(*) FILTER (WHERE event_type = 'upload_started')    AS total_uploads,
+      COUNT(*) FILTER (WHERE event_type = 'completed')         AS succeeded,
+      COUNT(*) FILTER (WHERE event_type = 'failed')            AS failed,
+      AVG(duration_ms) FILTER (WHERE event_type = 'completed') AS avg_processing_ms
+    FROM document_processing_events
+    WHERE created_at >= NOW() - $1::interval
+  `, [interval]);
+
+  const row = rows[0]!;
+  const total = parseInt(row.total_uploads, 10);
+  const succeeded = parseInt(row.succeeded, 10);
+  const failed = parseInt(row.failed, 10);
+
+  return {
+    range,
+    totalUploads: total,
+    succeeded,
+    failed,
+    successRate: total > 0 ? succeeded / total : 0,
+    avgProcessingMs: row.avg_processing_ms ? parseFloat(row.avg_processing_ms) : null,
+    generatedAt: new Date().toISOString(),
+  };
+}