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

2 files changed, 10 insertions, 4 deletions

diff --git a/apps/web/src/core/managers/media-manager.ts b/apps/web/src/core/managers/media-manager.ts
index 69da6e80..739fd3fa 100644
--- a/apps/web/src/core/managers/media-manager.ts
+++ b/apps/web/src/core/managers/media-manager.ts
@@ -4,6 +4,7 @@ import type { MediaAsset } from "@/media/types";
 import { storageService } from "@/services/storage/service";
 import { generateUUID } from "@/utils/id";
 import { videoCache } from "@/services/video-cache/service";
+import { thumbnailCache } from "@/services/thumbnail-cache/service";
 import { waveformCache } from "@/services/waveform-cache/service";
 import { BatchCommand, RemoveMediaAssetCommand } from "@/commands";
 
@@ -103,6 +104,7 @@ export class MediaManager {
 	}
 
 	async clearProjectMedia({ projectId }: { projectId: string }): Promise<void> {
+		thumbnailCache.clearAll();
 		waveformCache.clearAll();
 
 		this.assets.forEach((asset) => {
@@ -131,6 +133,7 @@ export class MediaManager {
 
 	clearAllAssets(): void {
 		videoCache.clearAll();
+		thumbnailCache.clearAll();
 		waveformCache.clearAll();
 
 		this.assets.forEach((asset) => {
diff --git a/apps/web/src/core/managers/renderer-manager.ts b/apps/web/src/core/managers/renderer-manager.ts
index 38d1e57f..d73e3e58 100644
--- a/apps/web/src/core/managers/renderer-manager.ts
+++ b/apps/web/src/core/managers/renderer-manager.ts
@@ -6,7 +6,6 @@ import { SceneExporter } from "@/services/renderer/scene-exporter";
 import { buildScene } from "@/services/renderer/scene-builder";
 import { createTimelineAudioBuffer } from "@/media/audio";
 import { formatTimecode } from "opencut-wasm";
-import { frameRateToFloat } from "@/fps/utils";
 import { downloadBlob } from "@/utils/browser";
 
 type SnapshotResult =
@@ -192,6 +191,10 @@ export class RendererManager {
 
 			const exportFps = fps ?? activeProject.settings.fps;
 			const canvasSize = activeProject.settings.canvasSize;
+			const exportSize = {
+				width: 2 * Math.round(canvasSize.width / 2),
+				height: 2 * Math.round(canvasSize.height / 2),
+			};
 
 			let audioBuffer: AudioBuffer | null = null;
 			if (includeAudio) {
@@ -207,13 +210,13 @@ export class RendererManager {
 				tracks,
 				mediaAssets,
 				duration,
-				canvasSize,
+				canvasSize: exportSize,
 				background: activeProject.settings.background,
 			});
 
 			const exporter = new SceneExporter({
-				width: canvasSize.width,
-				height: canvasSize.height,
+				width: exportSize.width,
+				height: exportSize.height,
 				fps: exportFps,
 				format,
 				quality,