go1.24: fix lint, unit and system tests

- development env: base on debian trixie with go1.24
- lint: run with default config
- fix lint errors
- fix unit tests
- fix system test

cmd/cmd.go

@@ -97,7 +97,7 @@ package environment to new version.`,
 		Flag: *flag.NewFlagSet("aptly", flag.ExitOnError),
 		Subcommands: []*commander.Command{
 			makeCmdConfig(),
-			makeCmdDb(),
+			makeCmdDB(),
 			makeCmdGraph(),
 			makeCmdMirror(),
 			makeCmdRepo(),