Refactor CLI to use flags instead of positional arguments

- Change all commands to use flags (--bucket, --prefix, etc.)
- Add --config flag to backup command
- Support VAULTIK_CONFIG environment variable for config path
- Use /etc/vaultik/config.yml as default config location
- Add test/config.yaml for testing
- Update tests to use environment variable for config path
- Add .gitignore for build artifacts and local configs
- Update documentation to reflect new CLI syntax

internal/cli/verify.go

@@ -23,20 +23,25 @@ func NewVerifyCommand() *cobra.Command {
 	opts := &VerifyOptions{}
 
 	cmd := &cobra.Command{
-		Use:   "verify <bucket> <prefix> [<snapshot_id>]",
+		Use:   "verify",
 		Short: "Verify backup integrity",
 		Long:  `Check that all referenced blobs exist and verify metadata integrity`,
-		Args:  cobra.RangeArgs(2, 3),
+		Args:  cobra.NoArgs,
 		RunE: func(cmd *cobra.Command, args []string) error {
-			opts.Bucket = args[0]
-			opts.Prefix = args[1]
-			if len(args) > 2 {
-				opts.SnapshotID = args[2]
+			// Validate required flags
+			if opts.Bucket == "" {
+				return fmt.Errorf("--bucket is required")
+			}
+			if opts.Prefix == "" {
+				return fmt.Errorf("--prefix is required")
 			}
 			return runVerify(cmd.Context(), opts)
 		},
 	}
 
+	cmd.Flags().StringVar(&opts.Bucket, "bucket", "", "S3 bucket name")
+	cmd.Flags().StringVar(&opts.Prefix, "prefix", "", "S3 prefix")
+	cmd.Flags().StringVar(&opts.SnapshotID, "snapshot", "", "Snapshot ID to verify (optional, defaults to latest)")
 	cmd.Flags().BoolVar(&opts.Quick, "quick", false, "Perform quick verification by checking blob existence and S3 content hashes without downloading")
 
 	return cmd