Major refactoring: Updated manifest format and renamed backup to snapshot

- Created manifest.go with proper Manifest structure including blob sizes
- Updated manifest generation to include compressed size for each blob
- Added TotalCompressedSize field to manifest for quick access
- Renamed backup package to snapshot for clarity
- Updated snapshot list to show all remote snapshots
- Remote snapshots not in local DB fetch manifest to get size
- Local snapshots not in remote are automatically deleted
- Removed backwards compatibility code (pre-1.0, no users)
- Fixed prune command to use new manifest format
- Updated all imports and references from backup to snapshot

internal/snapshot/module.go

@@ -0,0 +1,42 @@
+package snapshot
+
+import (
+	"git.eeqj.de/sneak/vaultik/internal/config"
+	"git.eeqj.de/sneak/vaultik/internal/database"
+	"git.eeqj.de/sneak/vaultik/internal/s3"
+	"github.com/spf13/afero"
+	"go.uber.org/fx"
+)
+
+// ScannerParams holds parameters for scanner creation
+type ScannerParams struct {
+	EnableProgress bool
+}
+
+// Module exports backup functionality as an fx module.
+// It provides a ScannerFactory that can create Scanner instances
+// with custom parameters while sharing common dependencies.
+var Module = fx.Module("backup",
+	fx.Provide(
+		provideScannerFactory,
+		NewSnapshotManager,
+	),
+)
+
+// ScannerFactory creates scanners with custom parameters
+type ScannerFactory func(params ScannerParams) *Scanner
+
+func provideScannerFactory(cfg *config.Config, repos *database.Repositories, s3Client *s3.Client) ScannerFactory {
+	return func(params ScannerParams) *Scanner {
+		return NewScanner(ScannerConfig{
+			FS:               afero.NewOsFs(),
+			ChunkSize:        cfg.ChunkSize.Int64(),
+			Repositories:     repos,
+			S3Client:         s3Client,
+			MaxBlobSize:      cfg.BlobSizeLimit.Int64(),
+			CompressionLevel: cfg.CompressionLevel,
+			AgeRecipients:    cfg.AgeRecipients,
+			EnableProgress:   params.EnableProgress,
+		})
+	}
+}