feat: add clip export with lossless/precise modes and export dialog

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

src/App.svelte

@@ -7,6 +7,7 @@
   import StatusBar from '$lib/components/StatusBar.svelte';
   import SetupWizard from '$lib/components/SetupWizard.svelte';
   import PreferencesPanel from '$lib/components/PreferencesPanel.svelte';
+  import ExportDialog from '$lib/components/ExportDialog.svelte';
   import { loadPreferences } from '$lib/stores/preferences.svelte';
   import { getSelectedClipId, removeClip } from '$lib/stores/clips.svelte';
   import { adjustShuttle } from '$lib/transport/playback';
@@ -111,6 +112,10 @@
   <PreferencesPanel onClose={() => (showPreferences = false)} />
 {/if}
 
+{#if showExportDialog}
+  <ExportDialog onClose={() => (showExportDialog = false)} />
+{/if}
+
 <div class="app-shell">
   <header class="toolbar">
     <UrlInput />
@@ -121,7 +126,7 @@
     <VideoPlayer />
     <TransportControls bind:this={transportControls} />
     <Timeline />
-    <ClipList />
+    <ClipList onExport={() => (showExportDialog = true)} />
   </main>
 
   <StatusBar />