fix: upgrade to Next.js 16.2.1 and resolve bundling issues

- Fixed client bundle contamination by moving child_process-dependent code
- Created standalone /api/robots/command route for SSH robot commands
- Created plugins router to replace robots.plugins for plugin management
- Added getStudyPlugins procedure to studies router
- Fixed trial.studyId references to trial.experiment.studyId
- Updated WizardInterface to use REST API for robot commands

src/components/experiments/designer/DesignerRoot.tsx

@@ -274,7 +274,7 @@ export function DesignerRoot({
     },
   });
 
-  const { data: studyPluginsRaw } = api.robots.plugins.getStudyPlugins.useQuery(
+  const { data: studyPluginsRaw } = api.studies.getStudyPlugins.useQuery(
     { studyId: experiment?.studyId ?? "" },
     { enabled: !!experiment?.studyId },
   );