- Add gofakes3 for in-process S3-compatible test server
- Create test server that runs on localhost:9999 with temp directory
- Implement basic S3 client wrapper with standard operations
- Add comprehensive tests for blob and metadata storage patterns
- Test cleanup properly removes temporary directories
- Use AWS SDK v2 for S3 operations with proper error handling
- Update bucket structure to include unencrypted blob manifest files
- Add <snapshot_id>.manifest.json.zst containing list of referenced blobs
- This enables pruning operations without requiring decryption keys
- Add snapshot management commands: list, rm, latest (stubs)
- Add --prune flag to backup command for automatic cleanup
- Update DESIGN.md to document manifest format and updated prune flow
