fix: await onDropMedia, fix stale closure deps, surface errors in TrackLane

- Import ActionResult type from @openreel/core
- onDropMedia prop type now returns Promise<ActionResult> | void
- handleDrop now awaits onDropMedia so failures are visible
- Replace silent catch with console.error + toast.error on failure
- Add allTracks, playheadPosition, snapSettings to handleDrop useCallback deps
  to fix stale closure bug (calculateSnap was using stale snap/track state)

services/editor/apps/web/src/components/editor/timeline/TrackLane.tsx

@@ -5,6 +5,7 @@ import type {
   ShapeClip,
   SVGClip,
   StickerClip,
+  ActionResult,
 } from "@openreel/core";
 import { ClipComponent } from "./ClipComponent";
 import { TextClipComponent } from "./TextClipComponent";
@@ -28,7 +29,7 @@ interface TrackLaneProps {
   trackHeights: Map<string, number>;
   timelineRef: React.RefObject<HTMLDivElement>;
   onSelectClip: (clipId: string, addToSelection: boolean) => void;
-  onDropMedia: (trackId: string, mediaId: string, startTime: number) => void;
+  onDropMedia: (trackId: string, mediaId: string, startTime: number) => Promise<ActionResult> | void;
   onMoveClip: (
     clipId: string,
     newStartTime: number,
@@ -178,13 +179,18 @@ export const TrackLane: React.FC<TrackLaneProps> = ({
             snapSettings,
             pixelsPerSecond,
           );
-          onDropMedia(track.id, data.mediaId, snapResult.time);
+          const result = await onDropMedia(track.id, data.mediaId, snapResult.time);
+          if (result && !result.success) {
+            console.error("[TrackLane] Failed to add clip:", result.error);
+            toast.error("Failed to add clip", result.error?.message ?? "");
+          }
         }
-      } catch {
-        // Silently ignore parse errors
+      } catch (err) {
+        console.error("[TrackLane] Drop error:", err);
+        toast.error("Failed to add clip", String(err));
       }
     },
-    [track.id, track.name, pixelsPerSecond, scrollX, onDropMedia],
+    [track.id, track.name, pixelsPerSecond, scrollX, onDropMedia, allTracks, playheadPosition, snapSettings],
   );
 
   const handleResizeStart = useCallback(