fix(presentation): extract 12 handler violations to use cases

- TokenService port + JwtTokenService adapter; login/refresh return LoginResult
- delete get_token (dup of login); create_tokens helper removed
- type UpdateChannelRequest schedule_config/recycle_policy (no serde_json::Value)
- update_settings returns updated Vec; handler calls one use case
- config use case in application::config; handler maps DTO only
- SyncStatusEntry moved to api-types w/ From<LibrarySyncLogEntry>
- trigger_sync: Conflict error, drop sync_trigger.send from handler
- UpsertProviderCommand.config accepts Value; serialization in use case
- get_current_broadcast returns BroadcastWithChannel; one call
- get_stream_url resolves broadcast internally; handler single call

crates/presentation/src/handlers/channels.rs

@@ -74,30 +74,14 @@ pub async fn update_channel(
     Path(id): Path<uuid::Uuid>,
     Json(req): Json<UpdateChannelRequest>,
 ) -> Result<Json<ChannelResponse>, AppError> {
-    let schedule_config = req
-        .schedule_config
-        .map(|v| {
-            serde_json::from_value(v)
-                .map_err(|e| AppError(DomainError::ValidationError(format!("Invalid schedule_config: {e}"))))
-        })
-        .transpose()?;
-
-    let recycle_policy = req
-        .recycle_policy
-        .map(|v| {
-            serde_json::from_value(v)
-                .map_err(|e| AppError(DomainError::ValidationError(format!("Invalid recycle_policy: {e}"))))
-        })
-        .transpose()?;
-
     let cmd = UpdateChannelCommand {
         channel_id: id.into(),
         owner_id: user.id(),
         name: req.name,
         description: req.description.map(Some),
         timezone: req.timezone,
-        schedule_config,
-        recycle_policy,
+        schedule_config: req.schedule_config.map(Into::into),
+        recycle_policy: req.recycle_policy,
         auto_schedule: req.auto_schedule,
     };
     let channel = application::channels::update::execute(&state.channel_command_deps, cmd).await?;