完善项目页弹性布局

固定项目列表表头高度避免被压缩
恢复无窗口壳渲染时的视口高度回退
保留窗口壳内容区的百分比高度覆盖

apps/ai-game-creator-shell/src/styles.css

@@ -826,7 +826,7 @@ textarea {
   width: calc(100vw - var(--launcher-sidebar-width));
   max-width: none;
   flex: 1 1 auto;
-  height: 100%;
+  height: 100dvh;
   min-height: 0;
   margin: 0;
   padding: 92px 28px 24px;
@@ -836,7 +836,7 @@ textarea {
 .launcher-main:has(.launcher-projects-page) {
   display: flex;
   flex-direction: column;
-  height: 100%;
+  height: 100dvh;
   min-height: 0;
   padding-bottom: 0;
 }
@@ -1030,6 +1030,7 @@ textarea {
 
 .launcher-project-table-header {
   height: 42px;
+  flex-shrink: 0;
   padding: 0 14px;
   border-bottom: 1px solid var(--platform-surface-border);
   background: color-mix(