fix(web,gateway): close P3 re-review#3 findings — sanitize command errors, harden turn-lock & caps

apps/gateway/src/commands/command-executor.service.ts

@@ -160,7 +160,12 @@ export class CommandExecutorService {
       }
     } catch (err) {
       this.logger.error(`Command /${command} failed: ${err}`);
-      return { command, conversationId, success: false, message: String(err) };
+      return {
+        command,
+        conversationId,
+        success: false,
+        message: 'Command failed due to an internal error.',
+      };
     }
   }