Add tablet landscape layout and allow PWA horizontal orientation.

Split mobile and tablet breakpoints, restore desktop-style reading on landscape tablets, and lock Android tablet apps to landscape.

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

.vitepress/theme/tablet-landscape.ts

@@ -0,0 +1,25 @@
+/** Android 平板 PWA 安装后默认锁定横屏 */
+export function initTabletLandscape() {
+  if (typeof window === 'undefined') return
+
+  function tryLockLandscape() {
+    const isStandalone =
+      window.matchMedia('(display-mode: standalone)').matches ||
+      (window.navigator as Navigator & { standalone?: boolean }).standalone
+
+    if (!isStandalone || !/Android/i.test(navigator.userAgent)) return
+
+    const shortestSide = Math.min(window.screen.width, window.screen.height)
+    if (shortestSide < 600) return
+
+    const lock = screen.orientation?.lock?.bind(screen.orientation)
+    if (!lock) return
+
+    lock('landscape-primary').catch(() => {
+      lock('landscape').catch(() => {})
+    })
+  }
+
+  tryLockLandscape()
+  window.addEventListener('orientationchange', tryLockLandscape)
+}