feat(dictation): surface "Talk now, think later" empty state and hide post-transcript actions

Reduces first-run cognitive load. Save / Copy / Clear / Export now appear only
once the user has a transcript or is recording, sliding in via animate-fade-in
(brand --duration-ui + ease-out-quart). Template and Extract Tasks remain
always-visible because they shape transcription rather than acting on completed
content.

Empty state now leads with the catchphrase as a brand statement
(font-display italic 28px) with the hotkey hint demoted to body-font tertiary.
EmptyState gains an optional headline prop; callers without it render unchanged.

src/lib/components/EmptyState.svelte

@@ -1,12 +1,17 @@
 <script>
-  let { icon: Icon = null, message = '', actionLabel = '', onAction = null } = $props();
+  let { icon: Icon = null, headline = '', message = '', actionLabel = '', onAction = null } = $props();
 </script>
 
-<div class="flex flex-col items-center justify-center gap-4 py-16 text-text-secondary">
+<div class="flex flex-col items-center justify-center gap-3 py-16 text-text-secondary">
   {#if Icon}
-    <Icon size={48} strokeWidth={1} class="opacity-40" aria-hidden="true" />
+    <Icon size={48} strokeWidth={1} class="opacity-40 mb-1" aria-hidden="true" />
+  {/if}
+  {#if headline}
+    <p class="font-display italic text-[28px] text-text text-center leading-tight">{headline}</p>
+  {/if}
+  {#if message}
+    <p class="text-center max-w-xs leading-relaxed {headline ? 'text-text-tertiary' : ''}">{message}</p>
   {/if}
-  <p class="text-center max-w-xs leading-relaxed">{message}</p>
   {#if actionLabel && onAction}
     <button onclick={onAction}
       class="px-4 py-2 rounded-lg bg-accent text-bg text-sm font-medium hover:bg-accent-hover"