Add comprehensive tests for hackathon service functionality

- Implemented tests for creating, retrieving, updating, and deleting hackathons.
- Added validation tests for hackathon creation and updates.
- Included tests for hackathon events and timelines, ensuring proper handling of edge cases.
- Created tests for hackathon submissions, including validation and submission status updates.
- Organized tests into a dedicated module for better structure and maintainability.

imphnen-backend/src/bin/seeder.rs

@@ -20,6 +20,7 @@ fn main() -> Result<(), Box<dyn Error>> {
 	run_seed("seed_roles_permissions")?;
 	run_seed("seed_users")?;
 	run_seed("seed_events")?;
+	run_seed("seed_hackathons")?;
 	run_seed("seed_gacha_rolls")?;
 	run_seed("seed_mentor_user")?;
 	println!("\n✅ All seeding completed successfully.");