fix(welcome): 欢迎页 - 补贡献者锚点并清掉已忽略的 Playwright 产物

导航增加贡献者定位，同时删除已被 gitignore 的本地验证截图，避免继续跟踪输出目录。

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

web/src/pages/welcome/contributors-card.tsx

@@ -10,7 +10,7 @@ export function WelcomeContributorsCard() {
     if (!welcomeContributors.length) return null;
 
     return (
-        <section className="welcome-contributors" aria-labelledby="welcome-contributors-title">
+        <section id="contributors" className="welcome-contributors" aria-labelledby="welcome-contributors-title">
             <CometCard containerClassName="welcome-contributors-perspective" className="welcome-contributors-card" rotateDepth={3.5} translateDepth={3}>
                 <div className="welcome-contributors-heading">
                     <span className="welcome-contributors-kicker">

web/src/pages/welcome/index.tsx

@@ -106,6 +106,7 @@ function WelcomeExperience({ look, brandName, onLookChange }: { look: WelcomeLoo
                 </a>
                 <nav className={menu ? "welcome-nav is-open" : "welcome-nav"} aria-label="首页导航">
                     <a href="#workbench" onClick={() => setMenu(false)}>工作台</a>
+                    <a href="#contributors" onClick={() => setMenu(false)}>贡献者</a>
                     <a href={github} target="_blank" rel="noreferrer">GitHub<ArrowUpRight size={13} /></a>
                 </nav>
                 <Button className="welcome-header-cta" type="primary" href="/create" icon={<ArrowUpRight size={16} />} iconPlacement="end">开始创作</Button>

web/src/pages/welcome/welcome.css

@@ -518,6 +518,7 @@ body:has(.welcome-page) {
     width: 100%;
     max-width: 1280px;
     margin: 48px auto 0;
+    scroll-margin-top: calc(var(--welcome-header-height) + 16px);
     text-align: left;
 }
 .welcome-contributors-perspective {