Add 13 test cases for convertPBSSnapshots covering:
- Empty/nil input handling
- Basic snapshot field mapping
- Files as string array
- Files as object array with filename field
- Invalid file objects ignored gracefully
- Verification status as string ("ok" vs other)
- Verification status as object with state field
- Verification object without state field
- Multiple snapshots with unique IDs
- Empty namespace handling in ID generation
- Container (ct) backup type
Coverage: convertPBSSnapshots 0% -> 100%
