feat(web): Field 标签自动关联控件 + 全局壳无障碍(skip link/设置可访问名/抽屉焦点归还)

apps/web/components/AppShell.tsx

@@ -33,6 +33,12 @@ export function AppShell({
       className="min-h-screen"
       style={{ ["--chrome" as string]: projectId ? "7rem" : "4rem" }}
     >
+      <a
+        href="#main"
+        className="sr-only focus:not-sr-only focus:absolute focus:left-4 focus:top-4 focus:z-50 focus:rounded focus:border focus:border-line focus:bg-panel focus:px-3 focus:py-2 focus:text-sm focus:text-ink focus:shadow-paper"
+      >
+        跳到正文
+      </a>
       <header className="flex h-16 items-center gap-4 border-b border-line bg-panel px-4 sm:px-6">
         <NavDrawer projectId={projectId} activeNav={activeNav} />
         <Link
@@ -52,10 +58,15 @@ export function AppShell({
             {subtitle}
           </span>
         ) : null}
-        <nav className="ml-auto flex shrink-0 items-center gap-2 text-sm">
+        <nav
+          aria-label="快捷操作"
+          className="ml-auto flex shrink-0 items-center gap-2 text-sm"
+        >
           <ThemeToggle />
           <Link
             href="/settings/providers"
+            aria-label="设置"
+            title="设置"
             className={buttonClass({
               variant: "ghost",
               size: "sm",
@@ -72,7 +83,11 @@ export function AppShell({
       ) : null}
       <div className="flex">
         <LeftNav projectId={projectId} activeNav={activeNav} />
-        <main className="min-h-[calc(100vh-var(--chrome,4rem))] min-w-0 flex-1 bg-bg">
+        <main
+          id="main"
+          tabIndex={-1}
+          className="min-h-[calc(100vh-var(--chrome,4rem))] min-w-0 flex-1 bg-bg"
+        >
           {children}
         </main>
       </div>