refactor(reporting): enhance timezone handling and clean up migration

- Updated SQL queries in reporting controllers to join with the timezones table for accurate timezone retrieval.
- Refactored ReportingMembersController to extend ReportingControllerBaseWithTimezone for centralized timezone logic.
- Removed obsolete migration file that added a timezone column to the users table, as it is no longer needed.

worklenz-backend/src/migrations/add_user_timezone.sql

@@ -1,8 +0,0 @@
--- Add timezone column to users table
-ALTER TABLE users ADD COLUMN IF NOT EXISTS timezone VARCHAR(50) DEFAULT 'UTC';
-
--- Add index for better query performance
-CREATE INDEX IF NOT EXISTS idx_users_timezone ON users(timezone);
-
--- Update existing users to use their browser timezone (this would be done via application logic)
-COMMENT ON COLUMN users.timezone IS 'IANA timezone identifier (e.g., America/New_York, Asia/Tokyo)';