feat: add TRANSPORT_ENCRYPTION toggle for easier deployment

- Add TRANSPORT_ENCRYPTION env config (default: false)
- Allow HTTP/IP access when transport encryption is disabled
- Add /api/crypto/config endpoint to expose encryption status
- Update WebCryptoEnvironmentCheck with 'disabled' status
- Update ExchangeConfigModal and AITradersPage to allow form submission when disabled
- Add i18n translations for disabled status (EN/CN)
- Update README with two deployment modes documentation

config/config.go

@@ -16,6 +16,11 @@ type Config struct {
 	APIServerPort       int
 	JWTSecret           string
 	RegistrationEnabled bool
+
+	// Security configuration
+	// TransportEncryption enables browser-side encryption for API keys
+	// Requires HTTPS or localhost. Set to false for HTTP access via IP.
+	TransportEncryption bool
 }
 
 // Init initializes global configuration (from .env)
@@ -43,6 +48,12 @@ func Init() {
 		}
 	}
 
+	// Transport encryption: default false for easier deployment
+	// Set TRANSPORT_ENCRYPTION=true to enable (requires HTTPS or localhost)
+	if v := os.Getenv("TRANSPORT_ENCRYPTION"); v != "" {
+		cfg.TransportEncryption = strings.ToLower(v) == "true"
+	}
+
 	global = cfg
 }