fix: wire initial sync, oauth flow, and eliminate warnings

- Add token_file_exists() to ApiClient for sync token check
- App::new now checks for token on startup; shows DeviceAuth popup if missing
- Background thread starts OAuth Device Flow automatically when no token
- App::poll_auth() called each frame to detect auth completion
- Auth completion triggers SyncCommand::InitialSync
- run_initial_sync fetches all lists and tasks via Google Tasks API
- Stores results in local DB via replace_all_lists / replace_all_tasks
- App::check_initial_load() refreshes UI from DB after initial sync
- Removed all compile warnings (dead_code annotations)

src/main.rs

@@ -56,7 +56,18 @@ fn main() -> io::Result<()> {
         });
     });
 
+    // Trigger initial sync if already authenticated
+    if !app.needs_auth {
+        let _ = sync_tx.try_send(SyncCommand::InitialSync);
+    }
+
     while !app.should_quit {
+        // Poll auth status (non-blocking)
+        app.poll_auth();
+
+        // Check if initial sync has loaded data into DB
+        app.check_initial_load();
+
         terminal.draw(|frame| {
             let status = {
                 let guard = network_status.blocking_lock();
@@ -109,6 +120,9 @@ async fn run_sync_engine(
                     Some(SyncCommand::TriggerSync) => {
                         process_sync_queue(&db, &api, &network_status).await;
                     }
+                    Some(SyncCommand::InitialSync) => {
+                        run_initial_sync(&db, &api, &network_status).await;
+                    }
                     Some(SyncCommand::Shutdown) | None => break,
                 }
             }
@@ -116,6 +130,29 @@ async fn run_sync_engine(
     }
 }
 
+async fn run_initial_sync(
+    db: &Arc<Db>,
+    api: &Arc<ApiClient>,
+    network_status: &Arc<Mutex<NetworkStatus>>,
+) {
+    *network_status.lock().await = NetworkStatus::Syncing;
+
+    match api.fetch_lists().await {
+        Ok(lists) => {
+            db.replace_all_lists(&lists).ok();
+            for list in &lists {
+                if let Ok(tasks) = api.fetch_tasks(&list.id).await {
+                    db.replace_all_tasks(&list.id, &tasks).ok();
+                }
+            }
+            *network_status.lock().await = NetworkStatus::Online;
+        }
+        Err(_) => {
+            *network_status.lock().await = NetworkStatus::Offline;
+        }
+    }
+}
+
 async fn process_sync_queue(
     db: &Arc<Db>,
     api: &Arc<ApiClient>,