refactor(chat): align chat header and input bar with Dart source

src/app/chat/components/chat-input-bar.module.css

@@ -1,35 +1,32 @@
-/* ChatInputBar 输入栏容器样式 */
+/* ChatInputBar 输入栏容器样式（与 Dart chat_input_bar.dart 对齐） */
 
+/* 外层：focused 时加 padding-top + 粉色背景 + 阴影 */
 .bar {
   flex: 0 0 auto;
-  padding: var(--spacing-3, 12px) var(--spacing-5, 20px) var(--spacing-5, 20px);
-  background: var(--color-input-bar-background, rgba(0, 0, 0, 0.4));
-  backdrop-filter: blur(8px);
-  border-top: 1px solid var(--color-chat-input-border, rgba(255, 255, 255, 0.12));
-  display: flex;
-  flex-direction: column;
-  gap: var(--spacing-2, 8px);
+  padding: 0 var(--spacing-lg, 16px) var(--spacing-lg, 16px);
+  background: transparent;
+  transition: padding-top 0.2s ease, background-color 0.2s ease,
+    box-shadow 0.2s ease;
 }
 
+.barFocused {
+  padding-top: var(--spacing-md, 12px);
+  background: #feeff2;
+  box-shadow: 0 4px 12px var(--color-input-box-shadow, rgba(0, 0, 0, 0.1));
+}
+
+/* 内层：白底 + 大圆角（Dart AppRadius.radius32）+ focused 时 accent 边框 */
 .row {
   display: flex;
   align-items: center;
-  gap: var(--spacing-2, 8px);
-  padding: var(--spacing-1, 4px) var(--spacing-3, 12px);
-  background: var(--color-bubble-background, #fff);
-  border-radius: 9999px;
-  border: 1px solid var(--color-chat-input-border, rgba(255, 255, 255, 0.2));
-  transition: border-color 0.2s, box-shadow 0.2s;
+  gap: var(--spacing-sm, 8px);
+  padding: var(--spacing-sm, 8px);
+  background: #fff;
+  border-radius: 32px;
+  border: 1px solid transparent;
+  transition: border-color 0.2s ease;
 }
 
 .rowFocused {
   border-color: var(--color-accent, #f84d96);
-  box-shadow: 0 4px 12px var(--color-input-shadow, rgba(0, 0, 0, 0.1));
-}
-
-.textFieldWrap {
-  flex: 1 1 auto;
-  min-width: 0;
-  display: flex;
-  align-items: center;
 }