✨ feat(stats): add user statistics to Prometheus metrics and Grafana

- Add user metrics to mana-core-auth MetricsService:
  - auth_users_total: Total registered users
  - auth_users_verified: Email-verified users
  - auth_users_created_today/this_week/this_month
- Create Grafana user-statistics dashboard with:
  - User overview stats (total, verified, verification rate, new today)
  - Registration period breakdown (today/week/month)
  - User growth trends over time
- Enhance telegram-stats-bot /users command:
  - Add yesterday comparison with trends
  - Add week-over-week comparison
  - Add mini bar chart for last 7 days registration
- Include user stats in daily Telegram report

services/mana-core-auth/src/metrics/metrics.service.ts

@@ -1,15 +1,28 @@
-import { Injectable, OnModuleInit } from '@nestjs/common';
+import { Injectable, Logger, OnModuleInit, OnModuleDestroy } from '@nestjs/common';
+import { ConfigService } from '@nestjs/config';
 import * as client from 'prom-client';
+import { count, eq, gte, and, isNull, sql } from 'drizzle-orm';
+import { getDb } from '../db/connection';
+import { users } from '../db/schema';
 
 @Injectable()
-export class MetricsService implements OnModuleInit {
+export class MetricsService implements OnModuleInit, OnModuleDestroy {
+	private readonly logger = new Logger(MetricsService.name);
 	private readonly register: client.Registry;
+	private updateInterval: NodeJS.Timeout | null = null;
 
 	// HTTP metrics
 	readonly httpRequestsTotal: client.Counter<string>;
 	readonly httpRequestDuration: client.Histogram<string>;
 
-	constructor() {
+	// User metrics
+	readonly usersTotal: client.Gauge<string>;
+	readonly usersVerified: client.Gauge<string>;
+	readonly usersCreatedToday: client.Gauge<string>;
+	readonly usersCreatedThisWeek: client.Gauge<string>;
+	readonly usersCreatedThisMonth: client.Gauge<string>;
+
+	constructor(private readonly configService: ConfigService) {
 		this.register = new client.Registry();
 
 		// Add default metrics (CPU, memory, event loop, etc.)
@@ -34,10 +47,113 @@ export class MetricsService implements OnModuleInit {
 			buckets: [0.001, 0.005, 0.01, 0.05, 0.1, 0.5, 1, 2, 5],
 			registers: [this.register],
 		});
+
+		// User statistics gauges
+		this.usersTotal = new client.Gauge({
+			name: 'auth_users_total',
+			help: 'Total number of registered users',
+			registers: [this.register],
+		});
+
+		this.usersVerified = new client.Gauge({
+			name: 'auth_users_verified',
+			help: 'Number of email-verified users',
+			registers: [this.register],
+		});
+
+		this.usersCreatedToday = new client.Gauge({
+			name: 'auth_users_created_today',
+			help: 'Number of users created today',
+			registers: [this.register],
+		});
+
+		this.usersCreatedThisWeek = new client.Gauge({
+			name: 'auth_users_created_this_week',
+			help: 'Number of users created this week',
+			registers: [this.register],
+		});
+
+		this.usersCreatedThisMonth = new client.Gauge({
+			name: 'auth_users_created_this_month',
+			help: 'Number of users created this month',
+			registers: [this.register],
+		});
 	}
 
-	onModuleInit() {
-		// Metrics are ready
+	async onModuleInit() {
+		// Update user metrics immediately and then every 60 seconds
+		await this.updateUserMetrics();
+		this.updateInterval = setInterval(() => this.updateUserMetrics(), 60000);
+	}
+
+	onModuleDestroy() {
+		if (this.updateInterval) {
+			clearInterval(this.updateInterval);
+			this.updateInterval = null;
+		}
+	}
+
+	private async updateUserMetrics() {
+		const databaseUrl = this.configService.get<string>('DATABASE_URL');
+		if (!databaseUrl) {
+			this.logger.warn('DATABASE_URL not configured, user metrics unavailable');
+			return;
+		}
+
+		try {
+			const db = getDb(databaseUrl);
+			const now = new Date();
+
+			// Start of today (midnight)
+			const startOfToday = new Date(now);
+			startOfToday.setHours(0, 0, 0, 0);
+
+			// Start of week (Monday)
+			const startOfWeek = new Date(now);
+			const day = startOfWeek.getDay();
+			const diff = startOfWeek.getDate() - day + (day === 0 ? -6 : 1);
+			startOfWeek.setDate(diff);
+			startOfWeek.setHours(0, 0, 0, 0);
+
+			// Start of month
+			const startOfMonth = new Date(now.getFullYear(), now.getMonth(), 1);
+
+			// Query all metrics in parallel
+			const [totalResult, verifiedResult, todayResult, weekResult, monthResult] = await Promise.all(
+				[
+					// Total users
+					db.select({ count: count() }).from(users).where(isNull(users.deletedAt)),
+					// Verified users
+					db
+						.select({ count: count() })
+						.from(users)
+						.where(and(isNull(users.deletedAt), eq(users.emailVerified, true))),
+					// Users created today
+					db
+						.select({ count: count() })
+						.from(users)
+						.where(and(isNull(users.deletedAt), gte(users.createdAt, startOfToday))),
+					// Users created this week
+					db
+						.select({ count: count() })
+						.from(users)
+						.where(and(isNull(users.deletedAt), gte(users.createdAt, startOfWeek))),
+					// Users created this month
+					db
+						.select({ count: count() })
+						.from(users)
+						.where(and(isNull(users.deletedAt), gte(users.createdAt, startOfMonth))),
+				]
+			);
+
+			this.usersTotal.set(totalResult[0].count);
+			this.usersVerified.set(verifiedResult[0].count);
+			this.usersCreatedToday.set(todayResult[0].count);
+			this.usersCreatedThisWeek.set(weekResult[0].count);
+			this.usersCreatedThisMonth.set(monthResult[0].count);
+		} catch (error) {
+			this.logger.error('Failed to update user metrics:', error);
+		}
 	}
 
 	async getMetrics(): Promise<string> {