feat: Add gcloud-style command grouping to gt help output

Organize 43 commands into 7 logical groups using cobra's built-in
AddGroup/GroupID feature:

- Work Management: spawn, sling, hook, handoff, done, mol, mq, etc.
- Agent Management: mayor, witness, refinery, deacon, polecat, etc.
- Communication: mail, nudge, broadcast, peek
- Services: daemon, start, stop, up, down, shutdown
- Workspace: rig, crew, init, install, git-init, namepool
- Configuration: account, theme, hooks, issue, completion
- Diagnostics: status, doctor, prime, version, help

Also renamed molecule to mol as the primary command name
(molecule is now an alias).

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

internal/cmd/root.go

@@ -32,10 +32,36 @@ func Execute() {
 	}
 }
 
+// Command group IDs - used by subcommands to organize help output
+const (
+	GroupWork      = "work"
+	GroupAgents    = "agents"
+	GroupComm      = "comm"
+	GroupServices  = "services"
+	GroupWorkspace = "workspace"
+	GroupConfig    = "config"
+	GroupDiag      = "diag"
+)
+
 func init() {
 	// Enable prefix matching for subcommands (e.g., "gt ref at" -> "gt refinery attach")
 	cobra.EnablePrefixMatching = true
 
+	// Define command groups (order determines help output order)
+	rootCmd.AddGroup(
+		&cobra.Group{ID: GroupWork, Title: "Work Management:"},
+		&cobra.Group{ID: GroupAgents, Title: "Agent Management:"},
+		&cobra.Group{ID: GroupComm, Title: "Communication:"},
+		&cobra.Group{ID: GroupServices, Title: "Services:"},
+		&cobra.Group{ID: GroupWorkspace, Title: "Workspace:"},
+		&cobra.Group{ID: GroupConfig, Title: "Configuration:"},
+		&cobra.Group{ID: GroupDiag, Title: "Diagnostics:"},
+	)
+
+	// Put help and completion in a sensible group
+	rootCmd.SetHelpCommandGroupID(GroupDiag)
+	rootCmd.SetCompletionCommandGroupID(GroupConfig)
+
 	// Global flags can be added here
 	// rootCmd.PersistentFlags().StringVar(&cfgFile, "config", "", "config file")
 }