Add custom types, version command, and restore --verify flag

- Add internal/types package with type-safe wrappers for IDs, hashes,
  paths, and credentials (FileID, BlobID, ChunkHash, etc.)
- Implement driver.Valuer and sql.Scanner for UUID-based types
- Add `vaultik version` command showing version, commit, go version
- Add `--verify` flag to restore command that checksums all restored
  files against expected chunk hashes with progress bar
- Remove fetch.go (dead code, functionality in restore)
- Clean up TODO.md, remove completed items
- Update all database and snapshot code to use new custom types

internal/vaultik/integration_test.go

@@ -14,6 +14,7 @@ import (
 	"git.eeqj.de/sneak/vaultik/internal/log"
 	"git.eeqj.de/sneak/vaultik/internal/snapshot"
 	"git.eeqj.de/sneak/vaultik/internal/storage"
+	"git.eeqj.de/sneak/vaultik/internal/types"
 	"github.com/spf13/afero"
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
@@ -184,7 +185,11 @@ func TestEndToEndBackup(t *testing.T) {
 
 	// Create test configuration
 	cfg := &config.Config{
-		SourceDirs:       []string{"/home/user"},
+		Snapshots: map[string]config.SnapshotConfig{
+			"test": {
+				Paths: []string{"/home/user"},
+			},
+		},
 		Exclude:          []string{"*.tmp", "*.log"},
 		ChunkSize:        config.Size(16 * 1024),  // 16KB chunks
 		BlobSizeLimit:    config.Size(100 * 1024), // 100KB blobs
@@ -232,7 +237,7 @@ func TestEndToEndBackup(t *testing.T) {
 	snapshotID := "test-snapshot-001"
 	err = repos.WithTx(ctx, func(ctx context.Context, tx *sql.Tx) error {
 		snapshot := &database.Snapshot{
-			ID:             snapshotID,
+			ID:             types.SnapshotID(snapshotID),
 			Hostname:       "test-host",
 			VaultikVersion: "test-version",
 			StartedAt:      time.Now(),
@@ -352,7 +357,7 @@ func TestBackupAndVerify(t *testing.T) {
 	snapshotID := "test-snapshot-001"
 	err = repos.WithTx(ctx, func(ctx context.Context, tx *sql.Tx) error {
 		snapshot := &database.Snapshot{
-			ID:             snapshotID,
+			ID:             types.SnapshotID(snapshotID),
 			Hostname:       "test-host",
 			VaultikVersion: "test-version",
 			StartedAt:      time.Now(),