feat: Enhance Rclone command configuration with pre-rendered flags and region support

- Added fields for pre-rendering flags in the config form, allowing for better user experience during edits.
- Updated Rclone command options to accept current command ID for pre-selection.
- Introduced region input fields for MinIO source and destination forms, enhancing configuration flexibility.
- Modified backend logic to handle region parameters when generating Rclone configurations.
- Improved flag handling by parsing selected flags and values for better state management in the UI.

internal/db/transfer_config_store.go

@@ -141,6 +141,10 @@ func (db *DB) GenerateRcloneConfig(config *TransferConfig) error {
 			"--config", configPath,
 			"--log-level", "ERROR",
 		}
+		// Add region if specified
+		if config.SourceRegion != "" {
+			args = append(args, "region", config.SourceRegion)
+		}
 		cmd := exec.Command(rclonePath, args...)
 		if output, err := cmd.CombinedOutput(); err != nil {
 			return fmt.Errorf("failed to create source config (minio): %v\nOutput: %s", err, output)
@@ -212,6 +216,10 @@ func (db *DB) GenerateRcloneConfig(config *TransferConfig) error {
 			"--config", configPath,
 			"--log-level", "ERROR",
 		}
+		// Add region if specified
+		if config.DestRegion != "" {
+			args = append(args, "region", config.DestRegion)
+		}
 		cmd := exec.Command(rclonePath, args...)
 		if output, err := cmd.CombinedOutput(); err != nil {
 			return fmt.Errorf("failed to create destination config (minio): %v\nOutput: %s", err, output)