feat: enhance type organization and import structure

- Added detailed tasks in `TODO.md` for isolating and organizing types/interfaces across various services, including analytics, task management, and integrations.
- Updated imports in multiple files to use the new `@/services/core/database` path for consistency.
- Ensured all type imports are converted to `import type { ... }` where applicable for better clarity and performance.

src/services/integrations/jira/scheduler.ts

@@ -1,4 +1,4 @@
-import { userPreferencesService } from '../../core/user-preferences';
+import { userPreferencesService } from '@/services/core/user-preferences';
 import { JiraService } from './jira';
 import { addMinutes, getToday } from '@/lib/date-utils';