feat: add Sub2API application for AI API gateway platform

- Add Sub2API 1Panel application configuration
- Support subscription quota distribution, API Key management, billing and load balancing
- Include docker-compose.yml, data.yml, README documentation and logo
- Support amd64 and arm64 architectures

apps/sub2api/README_en.md

@@ -0,0 +1,61 @@
+# Sub2API
+
+AI API Gateway Platform for subscription quota distribution.
+
+## Features
+
+- Multi-Account Management - Support multiple upstream account types (OAuth, API Key)
+- API Key Distribution - Generate and manage API Keys for users
+- Precise Billing - Token-level usage tracking and cost calculation
+- Smart Scheduling - Intelligent account selection with sticky sessions
+- Concurrency Control - Per-user and per-account concurrency limits
+- Rate Limiting - Configurable request and token rate limits
+- Admin Dashboard - Web interface for monitoring and management
+- External System Integration - Embed external systems via iframe
+
+## Quick Start
+
+### Default Port
+
+- Web UI: 8080
+
+### Initial Setup
+
+After deployment, access `http://YOUR_SERVER_IP:8080` to run the setup wizard.
+
+**Database Connection Settings:**
+- PostgreSQL Host: `postgres` (use service name in Docker network, NOT localhost)
+- Redis Host: `redis` (use service name in Docker network, NOT localhost)
+- PostgreSQL Password: Please use a strong password
+
+**JWT Secret Requirements:**
+- Length must be at least 32 characters
+- Use a randomly generated strong password for production
+
+### Data Directory
+
+Application data is stored in Docker named volumes:
+- `postgres_data` - PostgreSQL database data
+- `redis_data` - Redis cache data
+- `./data` - Application configuration and data
+
+## Links
+
+- Website: https://sub2api.org
+- GitHub: https://github.com/Wei-Shaw/sub2api
+- Demo: https://demo.sub2api.org/
+
+## Important Notes
+
+1. **Database Connection**: In Docker deployment, PostgreSQL and Redis use service names (`postgres`, `redis`) for connection. Do NOT use `localhost`
+
+2. **JWT Secret**: Must be at least 32 characters, use a random string recommended
+
+3. **First Deployment**: If you encounter database connection errors, ensure:
+   - PostgreSQL container has fully started (wait about 10-30 seconds)
+   - Old corrupted data volumes are cleared (use `docker compose down -v`)
+
+4. **Disclaimer**:
+   - This project is for personal learning purposes only
+   - Users must comply with the Terms of Service of Anthropic, OpenAI, etc.
+   - Do not use for illegal purposes