feat(npcs): free rotate overlays and drop session zoom tools

Drag the top-edge handle to rotate the whole frame with the avatar; remove unused zoom controls from the session NPC window.

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

app/renderer/shared/materials/MaterialOverlay.module.css

@@ -110,3 +110,35 @@
 .close:hover {
   background: rgba(24, 24, 32, 0.9);
 }
+
+.frameRotate {
+  position: absolute;
+  left: 50%;
+  top: 0;
+  z-index: 3;
+  width: 28px;
+  height: 28px;
+  border: none;
+  border-radius: 8px;
+  background: rgba(12, 12, 16, 0.78);
+  color: #fff;
+  padding: 0;
+  cursor: grab;
+  display: grid;
+  place-items: center;
+  pointer-events: auto;
+  box-shadow: 0 0 0 1px rgba(0, 0, 0, 0.45);
+  transform: translate(-50%, -50%);
+}
+
+.frameRotate:hover {
+  background: rgba(24, 24, 32, 0.95);
+}
+
+.frameRotate:active {
+  cursor: grabbing;
+}
+
+.frameRotateSvg {
+  display: block;
+}