Fix 4 unused variable warnings

- Remove fetch_in_flight in apply_lifecycle (code now calls apply_started directly)
- Simplify Pending arm pane creation to is_none() check (pane_id was unused)
- Remove root_task binding in hydrate_owner_child_transcript (never referenced)
- Remove has_ambient_model binding in attach_execution_session_to_ambient_pane

Co-Authored-By: Oz <oz-agent@warp.dev>

Author: cephalonaut

app/src/ai/blocklist/orchestration_child_tracker.rs

@@ -264,7 +264,6 @@ impl OrchestrationChildTracker {
         ctx: &mut ModelContext<OrchestrationEventStreamer>,
     ) {
         let tracker_known = self.children.contains_key(&task_id);
-        let fetch_in_flight = self.metadata_fetches.contains(run_id);
         if tracker_known {
             let status = conversation_status_from_lifecycle_event_type(kind);
             // Write status through immediately so the pill bar badge reflects

app/src/pane_group/child_agent/hydration.rs

@@ -204,11 +204,12 @@ impl PaneGroup {
                 // generic cloud-agent composing zero state. Register so that
                 // process_pending_remote_child_hydrations re-drives when
                 // evict_and_refetch_task fires TasksUpdated with fresh data.
-                let Some(pane_id) =
-                    self.create_owner_loading_child_placeholder(child_conversation, ctx)
-                else {
+                if self
+                    .create_owner_loading_child_placeholder(child_conversation, ctx)
+                    .is_none()
+                {
                     return;
-                };
+                }
                 self.pending_remote_child_hydrations
                     .insert(task_id, child_id);
                 self.ensure_pending_ambient_restoration_subscription(ctx);
@@ -514,8 +515,6 @@ impl PaneGroup {
                     return;
                 }
             };
-            let root_task = merged.get_root_task();
-
             let blocks_cloud_followups =
                 task.as_ref().is_none_or(AmbientAgentTask::blocks_cloud_followups);
             match completed_child_presentation(access, blocks_cloud_followups) {

app/src/pane_group/mod.rs

@@ -7029,11 +7029,6 @@ impl PaneGroup {
             return false;
         };
 
-        let has_ambient_model = terminal_view
-            .as_ref(ctx)
-            .ambient_agent_view_model()
-            .is_some();
-
         if let Some(ambient_agent_view_model) = terminal_view
             .as_ref(ctx)
             .ambient_agent_view_model()