refactor: remove legacy scheduling and analytics code

- Deleted the scheduler module and its associated functions, transitioning to OS-level scheduling.
- Removed the Analytics module and its related interfaces, retaining only a placeholder for backward compatibility.
- Updated ConfigValidator to warn about legacy schedule and analytics configurations.
- Cleaned up StartupValidator to remove diagnostics and schedule validation logic.
- Adjusted Load.ts to handle legacy flags for diagnostics and analytics.
- Removed unused diagnostics capturing functionality.

setup/update/update.mjs

@@ -400,8 +400,7 @@ async function main() {
     code = await updateDocker()
   }
   
-  // CRITICAL FIX: Always exit with code, even from scheduler
-  // The scheduler expects the update script to complete and exit
+  // CRITICAL: Always exit with code so external schedulers can react correctly
   // Otherwise the process hangs indefinitely and gets killed by watchdog
   process.exit(code)
 }