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/humanization.md

@@ -147,10 +147,10 @@ Skip random days per week:
 ## 📚 Next Steps
 
 **Need vacation mode?**  
-→ See [Scheduler Vacation](./schedule.md#vacation-mode)
+→ See [Vacation settings](./config.md#vacation)
 
 **Want scheduling?**  
-→ **[Scheduler Guide](./schedule.md)**
+→ **[External Scheduling](./schedule.md)**
 
 **More security?**  
 → **[Security Guide](./security.md)**