fix(lint): remove unnecessary escape in core-web-vitals regex (no-useless-escape)

Caused CI failure (Lint job) on 5ce31ba, blocking Vercel deploy.
0 errors, 2 warnings now.

Author: BugHunter Agent

src/lib/performance/core-web-vitals.ts

@@ -71,7 +71,7 @@ export class LazyImageLoader {
               // Only allow http(s) absolute URLs and root-relative paths.
               // Explicitly reject protocol-relative (//) and javascript:/data:
               // to prevent scheme injection via data-src attributes.
-              if (/^https?:\/\//i.test(dataSrc) || /^\/[^\/]/.test(dataSrc)) {
+              if (/^https?:\/\//i.test(dataSrc) || /^\/[^/]/.test(dataSrc)) {
                 img.src = dataSrc;
                 img.removeAttribute('data-src');
               }