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/accounts.md

@@ -32,7 +32,7 @@
 ### Why Use TOTP?
 - ✅ **Automated login** — No manual code entry
 - ✅ **More secure** — Better than SMS
-- ✅ **Works 24/7** — Scheduler-friendly
+- ✅ **Works 24/7** — Ready for external schedulers
 
 ### How to Get Your TOTP Secret
 
@@ -178,7 +178,7 @@ export ACCOUNTS_JSON='{"accounts":[{"email":"test@example.com","password":"pass"
 → **[Security Guide](./security.md)** for best practices
 
 **Ready for automation?**  
-→ **[Scheduler Setup](./schedule.md)**
+→ **[External Scheduling](./schedule.md)**
 
 **Need proxies?**  
 → **[Proxy Guide](./proxy.md)**