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>

config/config.go

@@ -50,6 +50,20 @@ type LeverageConfig struct {
 	AltcoinLeverage int `json:"altcoin_leverage"` // 山寨币的杠杆倍数（主账户建议5-20，子账户≤5）
 }
 
+// LogConfig 日志配置
+type LogConfig struct {
+	Level    string          `json:"level"`    // 日志级别: debug, info, warn, error (默认: info)
+	Telegram *TelegramConfig `json:"telegram"` // Telegram推送配置（可选）
+}
+
+// TelegramConfig Telegram推送配置（简化版，只保留必需字段）
+type TelegramConfig struct {
+	Enabled  bool   `json:"enabled"`   // 是否启用（默认: false）
+	BotToken string `json:"bot_token"` // Bot Token
+	ChatID   int64  `json:"chat_id"`   // Chat ID
+	MinLevel string `json:"min_level"` // 最低日志级别，该级别及以上的日志会推送到Telegram（可选，默认: error）
+}
+
 // Config 总配置
 type Config struct {
 	Traders            []TraderConfig `json:"traders"`
@@ -60,6 +74,7 @@ type Config struct {
 	MaxDrawdown        float64        `json:"max_drawdown"`
 	StopTradingMinutes int            `json:"stop_trading_minutes"`
 	Leverage           LeverageConfig `json:"leverage"` // 杠杆配置
+	Log                *LogConfig     `json:"log"`      // 日志配置（可选）
 }
 
 // LoadConfig 从文件加载配置