Move agent section to fab (#6597)

frontend/shared/components/ChatFABWindow.css

@@ -0,0 +1,43 @@
+.chat-fab-window {
+  position: relative;
+  display: flex;
+  flex-direction: column;
+  width: 100%;
+  height: 100%;
+  /* Use Mantine variables in the editor; fall back to shared tokens in storybook */
+  background: var(--mantine-color-body, var(--color-surface, #ffffff));
+  border-radius: 16px;
+  border: 1px solid var(--border-subtle, var(--color-border, #e3e8ee));
+  box-shadow:
+    0 8px 32px rgba(15, 23, 42, 0.14),
+    0 2px 8px rgba(15, 23, 42, 0.06);
+  overflow: hidden;
+
+  /* Closed state: collapsed toward bottom-right origin */
+  opacity: 0;
+  transform: scale(0.9) translateY(14px);
+  pointer-events: none;
+  transform-origin: bottom right;
+  transition:
+    opacity 200ms ease,
+    transform 220ms cubic-bezier(0.32, 0.72, 0, 1);
+}
+
+.chat-fab-window--open {
+  opacity: 1;
+  transform: scale(1) translateY(0);
+  pointer-events: auto;
+}
+
+[data-mantine-color-scheme="dark"] .chat-fab-window,
+[data-theme="dark"] .chat-fab-window {
+  box-shadow:
+    0 8px 32px rgba(0, 0, 0, 0.38),
+    0 2px 8px rgba(0, 0, 0, 0.22);
+}
+
+@media (prefers-reduced-motion: reduce) {
+  .chat-fab-window {
+    transition: opacity 100ms ease;
+  }
+}