UI polish: Illuminated Transcript design language

- Fraunces serif for headings and assistant identity label
- Chat bubbles flipped: assistant responses elevated (card + left indigo
  accent + shadow), user prompts ghosted (transparent bg, muted text)
- AppLogo: book fill changed from text-color to indigo in light mode
- AppHeader: border-bottom removed; active nav uses underline accent
- NoteCard/TaskCard: border replaced with whisper indigo-tint shadow
- HomeView: dashboard-response uses left accent; progress bars indigo;
  empty-state decorative marker; project cards use shadow depth
- NotesListView: btn-new/btn-cta use indigo gradient + glow
- All primary CTA buttons: indigo gradient (135deg #6366f1 → #4f46e5)
  with box-shadow glow on hover
- Dark palette: navy (#1a1a2e family) → slate-indigo (#111113 family)
- Scrollbars: thin 4px indigo-tinted

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

frontend/src/components/NoteCard.vue

@@ -60,15 +60,15 @@ function goEdit() {
 .note-card {
   display: block;
   padding: 1rem;
-  border: 1px solid var(--color-border);
   border-radius: var(--radius-md);
   text-decoration: none;
   color: inherit;
   background: var(--color-bg-card);
-  transition: box-shadow 0.15s;
+  box-shadow: 0 1px 4px rgba(0, 0, 0, 0.06), 0 0 0 1px rgba(99, 102, 241, 0.06);
+  transition: box-shadow 0.2s;
 }
 .note-card:hover {
-  box-shadow: 0 2px 8px var(--color-shadow);
+  box-shadow: 0 4px 16px rgba(0, 0, 0, 0.10), 0 0 0 1px rgba(99, 102, 241, 0.14);
 }
 
 /* Compact single-row layout */