chore: stage all pending work — caption styling, media server, processing modal, docs, summaries

Includes:
- Extended caption styling (font, shadow, dimmed color, bg toggle)
- Media server, subtitle downloader, VTT parser, processing modal
- Waveform tiers, thumbnail/timeline improvements, transport controls
- Hybrid download model, dependency management, clip export enhancements
- 21 chat summaries, 2 implementation plans, 2 design specs

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

src/lib/components/UrlInput.svelte

@@ -9,11 +9,17 @@
   } from '$lib/stores/videoSession.svelte';
 
   let inputValue = $state('');
+  let inputEl = $state<HTMLInputElement | null>(null);
+
+  function blurInput() {
+    inputEl?.blur();
+  }
 
   async function handleSubmit() {
     const trimmed = inputValue.trim();
     if (!trimmed) return;
 
+    blurInput();
     setResolving();
     try {
       const meta = await resolveUrl(trimmed);
@@ -43,6 +49,7 @@
 <div class="url-input-wrapper">
   <div class="url-input">
     <input
+      bind:this={inputEl}
       type="text"
       placeholder="Paste a video URL and press Enter…"
       bind:value={inputValue}