Add validation to command line flags + update system prompt handling

Renamed `applyPromptFlags` to `applyGenerationFlags` and added
`validateGenerationFlags`

pkg/cmd/retry.go

@@ -22,6 +22,11 @@ func RetryCmd(ctx *lmcli.Context) *cobra.Command {
 			return nil
 		},
 		RunE: func(cmd *cobra.Command, args []string) error {
+			err := validateGenerationFlags(ctx, cmd)
+			if err != nil {
+				return err
+			}
+
 			shortName := args[0]
 			conversation := cmdutil.LookupConversation(ctx, shortName)
 
@@ -68,6 +73,6 @@ func RetryCmd(ctx *lmcli.Context) *cobra.Command {
 
 	cmd.Flags().Int("offset", 0, "Offset from the last message to retry from.")
 
-	applyPromptFlags(ctx, cmd)
+	applyGenerationFlags(ctx, cmd)
 	return cmd
 }