fix: address final review findings (clip reset, codecs, paths, timeline)

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

src/lib/stores/videoSession.svelte.ts

@@ -8,6 +8,7 @@ import {
   extractWaveform,
 } from '$lib/bindings/mediaAnalysis';
 import { clearThumbnailCache } from '$lib/timeline/thumbnailRenderer';
+import { clearAll as clearAllClips } from '$lib/stores/clips.svelte';
 
 export type SessionStatus = 'idle' | 'resolving' | 'ready' | 'error';
 export type DownloadStatus = 'idle' | 'downloading' | 'complete' | 'failed';
@@ -32,6 +33,7 @@ export const session = $state({
 });
 
 export function setMetadata(meta: VideoMetadata) {
+  clearAllClips();
   session.url = meta.url;
   session.title = meta.title;
   session.duration = meta.duration;
@@ -73,6 +75,7 @@ export function setError(msg: string) {
 }
 
 export function setResolving() {
+  clearAllClips();
   clearMediaFields();
   session.status = 'resolving';
   session.error = null;