feat: Add support for Hetzner Storage Box integration

- Introduced new source and destination forms for Hetzner Storage Box, allowing users to configure their storage settings.
- Updated configuration generation logic to handle Hetzner, including necessary parameters such as host, port, username, and authentication type.
- Enhanced user interface with clear instructions and security notes for Hetzner, improving user experience and security awareness.
- Updated existing logic to accommodate Hetzner in rclone configuration generation for both source and destination types.

internal/rclone_service/rclone_service.go

@@ -116,6 +116,17 @@ func TestRcloneConnection(config db.TransferConfig, providerType string, dbInsta
 		if keyFile != "" {
 			createArgs = append(createArgs, "key_file", keyFile)
 		}
+	case "hetzner":
+		createArgs = append(createArgs, "host", host, "user", user, "pass", pass, "key_file", keyFile)
+		if port != 0 {
+			createArgs = append(createArgs, "port", fmt.Sprintf("%d", port))
+		}
+		if pass != "" {
+			createArgs = append(createArgs, "pass", pass)
+		}
+		if keyFile != "" {
+			createArgs = append(createArgs, "key_file", keyFile)
+		}
 	case "s3":
 		createArgs = append(createArgs, "provider", "AWS", "env_auth", "false")
 		if accessKey != "" {