Library: "Continue where you left off" row with a per-user setting

One fixed row above the library showing the five most recently read,
unfinished manga with the normal tiles (they stay in the grid as well).
It ignores search and filters, hides while sorted by "Recently read",
and can be turned off under Settings > Reading > Library page
(continueRow, default on).

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

public/app.css

@@ -94,7 +94,18 @@ main { max-width: 1200px; margin: 0 auto; padding: 16px; }
 .prog i { display: block; height: 100%; background: var(--accent); }
 .badge { position: absolute; top: 7px; right: 7px; background: var(--accent); color: #fff; font-size: 12px; font-weight: 700; padding: 2px 8px; border-radius: 10px; }
 .empty { text-align: center; padding: 60px 10px; }
+/* One fixed row; tiles sized like a six-column .grid, extra tiles scroll sideways instead of wrapping. */
+.continue-row { margin-bottom: 20px; padding-bottom: 16px; border-bottom: 1px solid var(--line); }
+.continue-banner {
+  display: inline-flex; gap: 6px; align-items: center; margin-bottom: 9px; padding: 2px 9px; border-radius: 10px;
+  background: color-mix(in srgb, var(--accent) 22%, var(--card)); color: #ffd8de; font-size: 12px; font-weight: 650;
+}
+.continue-tiles {
+  display: grid; grid-auto-flow: column; grid-auto-columns: max(140px, calc((100% - 80px) / 6)); gap: 16px;
+  overflow-x: auto; padding-bottom: 4px; scrollbar-width: thin;
+}
 @media (max-width: 560px) {
+  .continue-tiles { grid-auto-columns: calc((100% - 12px) / 2); gap: 12px; }
   main { padding: 12px; }
   .toolbar { flex-wrap: wrap; }
   .toolbar input { flex-basis: 100%; }