fix: clap CLI definitions and manpage generation

- add #[group(skip)] to all Parser-derived structs
- fix conflicts_with and arg definitions for correct CLI behavior
- refactor bin entry points to support manpage generation

core/man/start-cli/start-cli-registry-os-asset.1

@@ -0,0 +1,25 @@
+.ie \n(.g .ds Aq \(aq
+.el .ds Aq '
+.TH start-cli-registry-os-asset 1  "asset " 
+.SH NAME
+start\-cli\-registry\-os\-asset \- Commands to add, sign, or get registry assets
+.SH SYNOPSIS
+\fBstart\-cli registry os asset\fR [\fB\-h\fR|\fB\-\-help\fR] <\fIsubcommands\fR>
+.SH DESCRIPTION
+Commands to add, sign, or get registry assets
+.SH OPTIONS
+.TP
+\fB\-h\fR, \fB\-\-help\fR
+Print help
+.SH SUBCOMMANDS
+.TP
+start\-cli\-registry\-os\-asset\-add(1)
+Add asset to registry
+.TP
+start\-cli\-registry\-os\-asset\-get(1)
+Commands to download image, iso, or squashfs files
+.TP
+start\-cli\-registry\-os\-asset\-remove(1)
+.TP
+start\-cli\-registry\-os\-asset\-sign(1)
+Sign file and add to registry