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>

docs/getting-started/docker-deploy.en.md

@@ -50,7 +50,7 @@ docker compose --version  # Docker 24+ includes this, no separate installation n
 
 ```bash
 # Copy configuration template
-cp config.example.jsonc config.json
+cp config.json.example config.json
 
 # Edit configuration file with your API keys
 nano config.json  # or use any other editor
@@ -267,7 +267,7 @@ kill -9 <PID>
 # ~~ls -la config.json~~
 
 # ~~If not exists, copy template~~
-# ~~cp config.example.jsonc config.json~~
+# ~~cp config.json.example config.json~~
 
 *Note: Now using SQLite database for configuration storage, no longer need config.json*
 ```