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.1

@@ -0,0 +1,23 @@
+.ie \n(.g .ds Aq \(aq
+.el .ds Aq '
+.TH start-cli-registry-os 1  "os " 
+.SH NAME
+start\-cli\-registry\-os \- Commands related to OS assets and versions
+.SH SYNOPSIS
+\fBstart\-cli registry os\fR [\fB\-h\fR|\fB\-\-help\fR] <\fIsubcommands\fR>
+.SH DESCRIPTION
+Commands related to OS assets and versions
+.SH OPTIONS
+.TP
+\fB\-h\fR, \fB\-\-help\fR
+Print help
+.SH SUBCOMMANDS
+.TP
+start\-cli\-registry\-os\-asset(1)
+Commands to add, sign, or get registry assets
+.TP
+start\-cli\-registry\-os\-index(1)
+List OS versions index
+.TP
+start\-cli\-registry\-os\-version(1)
+Commands to add, remove, or list versions or version signers