fix(backup): preserve original filename in backup creation

Changed backup filename generation to preserve the original config filename
(e.g., config.toml, mcp.json) instead of hardcoding 'mcp.json' prefix.
This ensures Codex TOML backups are correctly named config.toml.{hostname}.{timestamp}.

- Updated create_backup() to use config_path.name instead of hardcoded prefix
- Updated BackupInfo.backup_name property to return actual filename
- Fixes backup restoration and listing for non-JSON config formats

Author: LittleCoinCoin

hatch/mcp_host_config/backup.py

@@ -53,7 +53,9 @@ def validate_file_exists(cls, v):
     @property
     def backup_name(self) -> str:
         """Get backup filename."""
-        return f"mcp.json.{self.hostname}.{self.timestamp.strftime('%Y%m%d_%H%M%S_%f')}"
+        # Extract original filename from backup path if available
+        # Backup filename format: {original_name}.{hostname}.{timestamp}
+        return self.file_path.name
 
     @property
     def age_days(self) -> int:
@@ -255,8 +257,10 @@ def create_backup(self, config_path: Path, hostname: str) -> BackupResult:
             host_backup_dir.mkdir(exist_ok=True)
 
             # Generate timestamped backup filename with microseconds for uniqueness
+            # Preserve original filename instead of hardcoding 'mcp.json'
             timestamp = datetime.now().strftime("%Y%m%d_%H%M%S_%f")
-            backup_name = f"mcp.json.{hostname}.{timestamp}"
+            original_filename = config_path.name
+            backup_name = f"{original_filename}.{hostname}.{timestamp}"
             backup_path = host_backup_dir / backup_name
 
             # Get original file size