feat(web): artist detail — category tabs, cover thumbs, album modal

Discography now has category tabs (All/Albums/Singles/EPs/Live/Comps/Other
with counts, defaults to Albums), cover-art thumbnails, and clicking an album
opens the AlbumModal with its tracklist. Detail GET gains ?all=true so the
client filters by tab (studio-only default still governs the artists-list
counts). Replaces the old flat date-sorted list + show-all toggle.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

web/src/app/design.css

@@ -293,3 +293,23 @@ nav.contents .sep { flex: 1; }
   .album-modal-head { grid-template-columns: 1fr; }
   .album-modal-cover { width: 150px; }
 }
+
+/* ── Tabs ─────────────────────────────────────────────── */
+.tabs { display: flex; gap: 2px; flex-wrap: wrap; border-bottom: 1px solid var(--rule); margin: 8px 0 18px; }
+.tab {
+  font-family: var(--mono); font-size: 0.68rem; letter-spacing: 0.12em; text-transform: uppercase;
+  color: var(--graphite); background: transparent; border: 0; border-bottom: 2px solid transparent;
+  padding: 9px 12px; cursor: pointer; margin-bottom: -1px;
+}
+.tab:hover { color: var(--ink); }
+.tab.active { color: var(--ink); border-bottom-color: var(--accent); }
+.tab .n { color: var(--rule-2); margin-left: 6px; }
+
+/* ── Discography row (cover thumb + click-to-modal) ───── */
+.disco-open {
+  display: flex; gap: 14px; align-items: center; background: transparent; border: 0; padding: 0;
+  cursor: pointer; text-align: left; color: inherit; min-width: 0;
+}
+.thumb { width: 46px; height: 46px; flex-shrink: 0; }
+.disco-open .rtitle { display: block; }
+.disco-open:hover .rtitle { text-decoration: underline; text-decoration-color: var(--accent); text-underline-offset: 3px; }