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/api/src/routes/channels/mod.rs

@@ -0,0 +1,55 @@
+//! Channel routes
+//!
+//! CRUD + schedule generation require authentication (Bearer JWT).
+//! Viewing endpoints (list, now, epg, stream) are intentionally public so the
+//! TV page works without login.
+
+use axum::{Router, routing::{get, post}};
+use chrono::{DateTime, Utc};
+use uuid::Uuid;
+
+use crate::{error::ApiError, state::AppState};
+
+mod broadcast;
+mod crud;
+mod schedule;
+
+pub fn router() -> Router<AppState> {
+    Router::new()
+        .route("/", get(crud::list_channels).post(crud::create_channel))
+        .route(
+            "/{id}",
+            get(crud::get_channel).put(crud::update_channel).delete(crud::delete_channel),
+        )
+        .route(
+            "/{id}/schedule",
+            post(schedule::generate_schedule).get(schedule::get_active_schedule),
+        )
+        .route("/{id}/now", get(broadcast::get_current_broadcast))
+        .route("/{id}/epg", get(broadcast::get_epg))
+        .route("/{id}/stream", get(broadcast::get_stream))
+}
+
+// ============================================================================
+// Shared helpers
+// ============================================================================
+
+pub(super) fn require_owner(channel: &domain::Channel, user_id: Uuid) -> Result<(), ApiError> {
+    if channel.owner_id != user_id {
+        Err(ApiError::Forbidden("You don't own this channel".into()))
+    } else {
+        Ok(())
+    }
+}
+
+pub(super) fn parse_optional_dt(
+    s: Option<String>,
+    default: DateTime<Utc>,
+) -> Result<DateTime<Utc>, ApiError> {
+    match s {
+        None => Ok(default),
+        Some(raw) => DateTime::parse_from_rfc3339(&raw)
+            .map(|dt| dt.with_timezone(&Utc))
+            .map_err(|_| ApiError::validation(format!("Invalid datetime '{}' — use RFC3339", raw))),
+    }
+}