fix(discord): harden slash command routing

src/plugins/commands.ts

@@ -322,9 +322,11 @@ export function listPluginCommands(): Array<{
 export function getPluginCommandSpecs(): Array<{
   name: string;
   description: string;
+  acceptsArgs: boolean;
 }> {
   return Array.from(pluginCommands.values()).map((cmd) => ({
     name: cmd.name,
     description: cmd.description,
+    acceptsArgs: cmd.acceptsArgs ?? false,
   }));
 }