feat: implement hybrid database architecture and frontend encryption

- Add PostgreSQL + SQLite hybrid database support with automatic switching
- Implement frontend AES-GCM + RSA-OAEP encryption for sensitive data
- Add comprehensive DatabaseInterface with all required methods
- Fix compilation issues with interface consistency
- Update all database method signatures to use DatabaseInterface
- Add missing UpdateTraderInitialBalance method to PostgreSQL implementation
- Integrate RSA public key distribution via /api/config endpoint
- Add frontend crypto service with proper error handling
- Support graceful degradation between encrypted and plaintext transmission
- Add directory creation for RSA keys and PEM parsing fixes
- Test both SQLite and PostgreSQL modes successfully

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: tinkle-community <tinklefund@gmail.com>

README.md

@@ -3,7 +3,7 @@
 [![Go Version](https://img.shields.io/badge/Go-1.21+-00ADD8?style=flat&logo=go)](https://golang.org/)
 [![React](https://img.shields.io/badge/React-18+-61DAFB?style=flat&logo=react)](https://reactjs.org/)
 [![TypeScript](https://img.shields.io/badge/TypeScript-5.0+-3178C6?style=flat&logo=typescript)](https://www.typescriptlang.org/)
-[![License](https://img.shields.io/badge/License-MIT-green.svg)](LICENSE)
+[![License](https://img.shields.io/badge/License-AGPL--3.0-blue.svg)](LICENSE)
 [![Backed by Amber.ac](https://img.shields.io/badge/Backed%20by-Amber.ac-orange.svg)](https://amber.ac)
 
 **Languages:** [English](README.md) | [中文](docs/i18n/zh-CN/README.md) | [Українська](docs/i18n/uk/README.md) | [Русский](docs/i18n/ru/README.md)
@@ -281,7 +281,7 @@ Docker automatically handles all dependencies (Go, Node.js, TA-Lib, SQLite) and
 #### Step 1: Prepare Configuration
 ```bash
 # Copy configuration template
-cp config.example.jsonc config.json
+cp config.json.example config.json
 
 # Edit and fill in your API keys
 nano config.json  # or use any editor
@@ -1240,7 +1240,15 @@ sudo apt-get install libta-lib0-dev
 
 ## 📄 License
 
-MIT License - See [LICENSE](LICENSE) file for details
+This project is licensed under the **GNU Affero General Public License v3.0 (AGPL-3.0)** - See [LICENSE](LICENSE) file for details.
+
+**What this means:**
+- ✅ You can use, modify, and distribute this software
+- ✅ You must disclose source code of your modifications
+- ✅ If you run a modified version on a server, you must make the source code available to users
+- ✅ All derivatives must also be licensed under AGPL-3.0
+
+For commercial licensing or questions, please contact the maintainers.
 
 ---