Add pending upload indicator to UI

This commit introduces a visual indicator in the UI to show when a case
has pending uploads.

The `WorkerSnapshot` struct has been updated to include a
`pending_case_ids` field, which is an `Arc<HashSet<Uuid>>`. This set
stores the IDs of cases that currently have files in the pending
directory.

The `run_loop` function now populates this set by scanning the pending
directory and collecting the `case_id`s of any files found. This
snapshot is then sent to the UI via the `worker_rx` channel.

In the `DoctateApp::ui` method, the `pending_ids` set is cloned from the
worker's snapshot. If a case's ID is present in this set, a distinct "⬆"
prefix and a yellow label are used to highlight it, signifying an
ongoing or pending upload. Otherwise, the standard label is used.

client-desktop/src/app.rs

@@ -483,6 +483,14 @@ impl DoctateApp {
             return None;
         }
 
+        // Pending-upload lookup for the badge. Cheap clone (Arc) from the
+        // worker's last published snapshot; empty set if no worker yet.
+        let pending_ids = self
+            .worker_rx
+            .as_ref()
+            .map(|rx| rx.borrow().pending_case_ids.clone())
+            .unwrap_or_default();
+
         let mut action = None;
         // Ready-for-new means the user-intent state is Idle AND no ffmpeg
         // instance is still flushing. Upload-queue depth does NOT gate.
@@ -499,7 +507,17 @@ impl DoctateApp {
                     .as_deref()
                     .map(str::to_owned)
                     .unwrap_or_else(|| "⏳".to_owned());
-                ui.label(format!("{time_str} · {oneliner}"));
+                let has_pending = pending_ids.contains(&marker.case_id);
+                let line = if has_pending {
+                    format!("⬆ {time_str} · {oneliner}")
+                } else {
+                    format!("{time_str} · {oneliner}")
+                };
+                if has_pending {
+                    ui.colored_label(egui::Color32::from_rgb(200, 140, 0), line);
+                } else {
+                    ui.label(line);
+                }
 
                 ui.horizontal(|ui| {
                     if ui