polish(design-v2): library tile is one connected card, Manage feels like a button

Each library tile becomes a single glass card containing the photo and
the Manage row with no gap — the Manage button bar sits below the photo
with its own dark-glass background and a 1px top divider so it reads as
a tappable footer. Manage-action ('Manage ▸') in yellow for affordance.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

frontend/src/styles/design-v2.scss

@@ -155,6 +155,43 @@
   .home-view__empty-title { font-family: var(--font-display-v2); }
   .library__add-btn { background: var(--color-primary); color: var(--color-primary-fg); }
 
+  // Library tile becomes a single connected card — photo and Manage button
+  // share the same surface, no gap between them. Manage gets a button-bar feel.
+  .library__item {
+    background: var(--color-surface);
+    border: 1px solid var(--color-border);
+    border-radius: var(--radius-md);
+    overflow: hidden;
+    gap: 0 !important;
+    box-shadow: 0 8px 20px -10px rgba(0,0,0,0.5);
+    backdrop-filter: saturate(160%) blur(20px);
+    -webkit-backdrop-filter: saturate(160%) blur(20px);
+  }
+  .library__thumb {
+    border-radius: 0 !important;
+  }
+  .library__manage {
+    background: rgba(0,0,0,0.25) !important;
+    border-top: 1px solid var(--color-border);
+    border-radius: 0 !important;
+    padding: var(--space-3) var(--space-4) !important;
+    transition: background var(--duration-fast) var(--ease-out);
+
+    &:hover { background: rgba(0,0,0,0.4) !important; }
+  }
+  .library__manage-summary {
+    color: var(--color-text-muted);
+    font-size: var(--text-sm);
+    font-family: var(--font-family);
+    b { color: var(--color-text); }
+  }
+  .library__manage-action {
+    color: var(--brand-yellow) !important;
+    font-weight: 700;
+    font-size: var(--text-sm);
+  }
+  .library__manage-lock { color: var(--color-text-muted); }
+
   // ── Settings polish ────────────────────────────────────────────────
   .settings {
     &__title { font-family: var(--font-display-v2); font-weight: 400; letter-spacing: 0.005em; }