feat: Add Admin Panel pattern for Telegram bots

[talkstream]

Summary

This PR adds a production-ready Admin Panel pattern for Telegram bots running on Cloudflare Workers. The pattern provides a secure web-based interface for bot administration without external dependencies.

Features

• 🔐 Telegram-based 2FA: Secure authentication using Telegram bot messages
• 🌐 HTML-based UI: No build tools required, works directly on Cloudflare Workers
• 🔑 Session Management: Secure sessions using KV storage
• 🛡️ Middleware Pattern: Protected routes with authentication middleware
• 📊 Dashboard Template: Ready-to-use dashboard with customizable statistics
• 🧪 Type-safe Testing: Helper functions for mocking D1 database in tests

Architecture

┌─────────────────┐     ┌─────────────────┐     ┌─────────────────┐
│   Web Browser   │────▶│  Admin Routes   │────▶│   KV Storage    │
└─────────────────┘     └─────────────────┘     └─────────────────┘
         │                       │                         │
         │                       ▼                         │
         │              ┌─────────────────┐               │
         └─────────────▶│  Auth Handler   │◀──────────────┘
                        └─────────────────┘
                                 │
                                 ▼
                        ┌─────────────────┐
                        │  Telegram Bot   │
                        └─────────────────┘

Usage

1. Bot owner uses /admin command
2. Bot generates temporary auth code (5 min TTL)
3. Admin opens web panel and enters ID + code
4. Session created with 24-hour expiration
5. Access to dashboard and management features

Example

See src/patterns/admin-panel/example/bot-with-admin.ts for a complete implementation.

Test plan

• All tests pass
• TypeScript strict mode compliance
• No domain-specific dependencies
• Comprehensive documentation
• Review by maintainers