Change FileProgress callback to channel-based progress

Replace callback-based progress reporting in Builder.AddFile with
channel-based FileHashProgress for consistency with EnumerateStatus
and ScanStatus patterns. Update scanner.go to use the new channel API.

internal/cli/mfer.go

@@ -117,10 +117,15 @@ func (mfa *CLIApp) run(args []string) {
 					},
 					&cli.StringFlag{
 						Name:    "output",
-						Value:   "./index.mf",
+						Value:   "./.index.mf",
 						Aliases: []string{"o"},
 						Usage:   "Specify output filename",
 					},
+					&cli.BoolFlag{
+						Name:    "force",
+						Aliases: []string{"f"},
+						Usage:   "Overwrite output file if it exists",
+					},
 					&cli.BoolFlag{
 						Name:    "progress",
 						Aliases: []string{"P"},
@@ -157,6 +162,41 @@ func (mfa *CLIApp) run(args []string) {
 					},
 				},
 			},
+			{
+				Name:      "freshen",
+				Usage:     "Update manifest with changed, new, and removed files",
+				ArgsUsage: "[manifest file]",
+				Action: func(c *cli.Context) error {
+					if !c.Bool("quiet") {
+						mfa.printBanner()
+					}
+					mfa.setVerbosity(verbosity)
+					return mfa.freshenManifestOperation(c)
+				},
+				Flags: []cli.Flag{
+					&cli.StringFlag{
+						Name:    "base",
+						Aliases: []string{"b"},
+						Value:   ".",
+						Usage:   "Base directory for resolving relative paths",
+					},
+					&cli.BoolFlag{
+						Name:    "FollowSymLinks",
+						Aliases: []string{"follow-symlinks"},
+						Usage:   "Resolve encountered symlinks",
+					},
+					&cli.BoolFlag{
+						Name:    "IgnoreDotfiles",
+						Aliases: []string{"ignore-dotfiles"},
+						Usage:   "Ignore any dot (hidden) files encountered",
+					},
+					&cli.BoolFlag{
+						Name:    "progress",
+						Aliases: []string{"P"},
+						Usage:   "Show progress during scanning and hashing",
+					},
+				},
+			},
 			{
 				Name:  "version",
 				Usage: "Show version",