Refactor schedule and user repositories into modular structure

- Moved schedule repository logic into separate modules for SQLite and PostgreSQL implementations.
- Created a mapping module for shared data structures and mapping functions in the schedule repository.
- Added new mapping module for user repository to handle user data transformations.
- Implemented PostgreSQL and SQLite user repository adapters with necessary CRUD operations.
- Added tests for user repository functionality, including saving, finding, and deleting users.

k-tv-backend/domain/src/value_objects/ids.rs

@@ -0,0 +1,6 @@
+use uuid::Uuid;
+
+pub type UserId = Uuid;
+pub type ChannelId = Uuid;
+pub type SlotId = Uuid;
+pub type BlockId = Uuid;