Add movement gallery wings with period interiors and expand timeline features.

Movement galleries split large catalogs into chronological wings (~55 works), use era-themed 3D interiors with side-wall windows, wing navigator on the back exit, and front archways between wings. Also adds painting annotations, timeline event guides, portrait hover highlights, and documentation/API updates.

Co-authored-by: Cursor <cursoragent@cursor.com>

client/src/components/TimelineEventGuides.css

@@ -0,0 +1,34 @@
+.timeline-event-guides {
+  position: absolute;
+  top: 78px;
+  left: 16px;
+  right: 16px;
+  bottom: 16px;
+  pointer-events: none;
+  z-index: 3;
+}
+
+.timeline-event-guide-line {
+  position: absolute;
+  top: 0;
+  bottom: 0;
+  width: 2px;
+  transform: translateX(-50%);
+  background: linear-gradient(
+    180deg,
+    rgba(255, 210, 120, 0.55) 0%,
+    rgba(255, 180, 90, 0.35) 35%,
+    rgba(255, 160, 80, 0.18) 100%
+  );
+  box-shadow: 0 0 8px rgba(255, 190, 100, 0.25);
+}
+
+.timeline-event-guide-span {
+  position: absolute;
+  top: 0;
+  bottom: 0;
+  background: rgba(180, 70, 55, 0.1);
+  border-left: 2px solid rgba(255, 150, 110, 0.35);
+  border-right: 2px solid rgba(255, 150, 110, 0.35);
+  border-radius: 2px;
+}