fix(ui): 调整输入栏浮层高度并统一/new页手机端间距

- 将 composer-avatar 与 floating-status-row 容器高度分别调整为 45px/34px，
  避免容器高度大于实际内容导致聊天区滚动高度虚增。
- 统一手机端 /new 页面输入栏上移量与欢迎语内边距为桌面端数值，
  修复手机端输入栏与欢迎语间距过大的问题。

static/src/components/input/InputComposer.vue

@@ -2968,7 +2968,7 @@ onBeforeUnmount(() => {
   align-items: flex-end;
   justify-content: flex-start;
   width: 45px;
-  height: 64px;
+  height: 45px;
   pointer-events: auto;
   color: var(--claude-text);
 }
@@ -2979,7 +2979,7 @@ onBeforeUnmount(() => {
   right: 49px;
   bottom: calc(100% + 6px);
   z-index: auto;
-  height: 64px;
+  height: 34px;
   display: flex;
   align-items: flex-end;
   justify-content: center;

static/src/styles/components/input/_composer.scss

@@ -1098,10 +1098,10 @@ body[data-theme='light'] {
     height: 44px;
   }
   .composer-container.blank-hero-mode {
-    transform: translateY(calc(-32vh + var(--composer-growth-height, 0px)));
+    transform: translateY(calc(-38vh + var(--composer-growth-height, 0px)));
   }
   .blank-hero-overlay {
-    padding-bottom: 136px;
+    padding-bottom: 160px;
   }
 }