Refactor: Asynchronous Data Seeding and Structured Data Files

[iqbalpa]

This PR refactors the application's data seeding process to improve startup performance and data organization.

Key Changes:

• Asynchronous Seeding: The utils.SeedTasks(db) call in cmd/main.go is now executed in a goroutine with
  sync.WaitGroup, allowing the application to start without waiting for the seeding process to complete.
• Dedicated Data Files:
  • Introduced internal/data/task.json with 100 dummy task entries.
  • Introduced internal/data/user.json with 10 dummy user entries.
  • Removed the generic internal/utils/data.json.
• Generic Seeder: The internal/utils/seeder.go has been updated to:
  • Define UserDataPath and TaskDataPath constants for the new data file locations.
  • Modify readFile to accept a filename, enabling reading from specific JSON files.
  • Make getDummyData generic to handle both task and user data.
  • Update SeedTasks to read and save dummy tasks and users from their respective new JSON files.

Benefits:

• Faster Application Startup: Asynchronous seeding prevents the main application from being blocked during data
  initialization.
• Improved Data Organization: Separating task and user data into dedicated JSON files provides a clearer and more
  maintainable structure.