feat: ripple-extend resize, timeline filmstrip, export hardening

Yesterday's verified web session (gates green: 316 tests, tsc, build):
- ripple-extend pushes right-hand chain on static-element resize
- per-position video filmstrip thumbnails with zoom-adaptive density
- fps-aware export bitrate, 2s keyframes, even-dim export canvas
- freeze frame uses fixed 3s duration, prompt removed

1 files changed, 2 insertions, 0 deletions

diff --git a/apps/web/src/commands/media/remove-media-asset.ts b/apps/web/src/commands/media/remove-media-asset.ts
index ab267f36..2180c302 100644
--- a/apps/web/src/commands/media/remove-media-asset.ts
+++ b/apps/web/src/commands/media/remove-media-asset.ts
@@ -4,6 +4,7 @@ import { toast } from "sonner";
 import type { MediaAsset } from "@/media/types";
 import { buildWaveformSourceKey } from "@/media/waveform-summary";
 import { storageService } from "@/services/storage/service";
+import { thumbnailCache } from "@/services/thumbnail-cache/service";
 import { videoCache } from "@/services/video-cache/service";
 import { waveformCache } from "@/services/waveform-cache/service";
 import { hasMediaId } from "@/timeline/element-utils";
@@ -67,6 +68,7 @@ export class RemoveMediaAssetCommand extends Command {
 		}
 
 		videoCache.clearVideo({ mediaId: this.assetId });
+		thumbnailCache.clearMedia({ mediaId: this.assetId });
 		waveformCache.clearSource({
 			sourceKey: buildWaveformSourceKey({
 				kind: "media",