fix(color): eliminate redundant dark: accent modifiers (R-8.29), resolve A-1/A-2/A-9 contrast issues, and implement C11-9 quality gate

refer_landing_page/components/Footer.tsx

@@ -50,7 +50,7 @@ export default function Footer() {
             경북대학교 IT대학 5호관(415동) 527호<br />
             <a
               href="mailto:sjkoh@knu.ac.kr"
-              className="draw-underline mt-2 inline-block text-ink hover:text-vermillion font-medium"
+              className="draw-underline mt-2 inline-block text-ink hover:text-vermillion-dark font-medium"
             >
               sjkoh@knu.ac.kr
             </a>
@@ -68,7 +68,7 @@ export default function Footer() {
                 </span>
                 <Link
                   href={l.href}
-                  className="text-sm text-ink-soft transition hover:text-vermillion"
+                  className="text-sm text-ink-soft transition hover:text-vermillion-dark"
                 >
                   {l.ko}{" "}
                   <span className="text-xs text-ink-mute">{l.en}</span>

refer_landing_page/components/Header.tsx

@@ -67,7 +67,7 @@ export default function Header() {
                   className={`group relative flex items-baseline gap-1.5 text-[0.78rem] font-semibold uppercase tracking-[0.18em] transition-all px-3 py-1.5 rounded-md ${
                     active
                       ? "bg-cobalt-dark text-white dark:text-ivory shadow-sm font-bold"
-                      : "text-ink hover:text-cobalt-dark dark:hover:text-cobalt hover:bg-paper/60"
+                      : "text-ink hover:text-cobalt-dark hover:bg-paper/60"
                   }`}
                 >
                   <span