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.

docs/update.md

@@ -96,8 +96,8 @@ npm run build
 **Need security tips?**  
 → **[Security Guide](./security.md)**
 
-**Setup scheduler?**  
-→ **[Scheduler Guide](./schedule.md)**
+**Need automation?**  
+→ **[External Scheduling](./schedule.md)**
 
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