feat: timeline zooms to clip region on cut-clip from Player mode

Co-authored-by: Cursor <cursoragent@cursor.com>

src/lib/components/Timeline.svelte

@@ -22,6 +22,14 @@
 
   type ClipDragTarget = { clipId: string; edge: 'start' | 'end' };
 
+  let {
+    zoomRegion,
+    onZoomApplied,
+  }: {
+    zoomRegion?: { start: number; end: number } | null;
+    onZoomApplied?: () => void;
+  } = $props();
+
   let canvas = $state<HTMLCanvasElement | null>(null);
   let minimapCanvas = $state<HTMLCanvasElement | null>(null);
   let containerEl = $state<HTMLDivElement | null>(null);
@@ -189,6 +197,19 @@
     }
   });
 
+  $effect(() => {
+    if (zoomRegion && session.duration > 0) {
+      const clipLen = zoomRegion.end - zoomRegion.start;
+      const pad = Math.max(clipLen * 0.2, 2);
+      const vs = Math.max(0, zoomRegion.start - pad);
+      const ve = Math.min(session.duration, zoomRegion.end + pad);
+      timelineState.visibleStart = vs;
+      timelineState.visibleEnd = ve;
+      timelineState.zoom = session.duration / (ve - vs);
+      onZoomApplied?.();
+    }
+  });
+
   $effect(() => {
     if (!containerEl) return;
     const observer = new ResizeObserver((entries) => {