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/infra/src/jellyfin/config.rs

@@ -0,0 +1,10 @@
+/// Connection details for a single Jellyfin instance.
+#[derive(Debug, Clone)]
+pub struct JellyfinConfig {
+    /// e.g. `"http://192.168.1.10:8096"` — no trailing slash
+    pub base_url: String,
+    /// Jellyfin API key (Settings → API Keys)
+    pub api_key: String,
+    /// The Jellyfin user ID used for library browsing
+    pub user_id: String,
+}