Splash: remove non-composited glow rings (fix mobile NO_LCP); cross-fade to content; nudge tracer target

- Drop the two animated glow rings: stroke-dashoffset is non-composited, so
  they repainted every frame next to the logo and prevented Lighthouse from
  settling on an LCP (mobile NO_LCP). The static box + pulsing glow remain.
- Splash now cross-fades into the content: on enter it becomes a fixed overlay
  and fades opacity to 0 over the revealed page, instead of a hard cut.
- Nebula tracer target moved up-and-left (computerX-1, computerY-1.5) so the
  streamers converge on the monitor screen, not below-right of it.
- Removed the now-unused splash-* keyframes.

apps/web/src/app/globals.css

@@ -227,16 +227,4 @@
     transition-duration: 0.01ms !important;
     scroll-behavior: auto !important;
   }
-}
-
-/* Splash hero idle animations as CSS (browser/compositor driven) instead of
-   framer-motion, so they cost no JS main-thread time. The reduced-motion block
-   above neutralizes them. */
-@keyframes splash-float { 0%, 100% { transform: translateY(0); } 50% { transform: translateY(-8px); } }
-@keyframes splash-breath { 0%, 100% { opacity: 0.9; } 50% { opacity: 1; } }
-@keyframes splash-ring-a { from { stroke-dashoffset: 0; } to { stroke-dashoffset: -1; } }
-@keyframes splash-ring-b { from { stroke-dashoffset: 0; } to { stroke-dashoffset: 1; } }
-.splash-float { animation: splash-float 6s ease-in-out infinite; }
-.splash-breath { animation: splash-breath 5s ease-in-out infinite; }
-.splash-ring-a { animation: splash-ring-a 5s linear infinite; }
-.splash-ring-b { animation: splash-ring-b 7s linear infinite; }
+}

apps/web/src/app/page.tsx

@@ -22,6 +22,10 @@ export default function Home() {
   // header, bottom nav, and background take over. Scrolling back up lands on the hero,
   // never the splash again.
   const [entered, setEntered] = useState(false);
+  // `splashUp` keeps the splash mounted through its fade-out; `leaving` triggers the
+  // cross-fade overlay (button path only).
+  const [splashUp, setSplashUp] = useState(true);
+  const [leaving, setLeaving] = useState(false);
   const splashRef = useRef<HTMLElement>(null);
   const restoreScroll = useRef(0);
 
@@ -31,6 +35,7 @@ export default function Home() {
   useIsoLayoutEffect(() => {
     if (window.matchMedia("(prefers-reduced-motion: reduce)").matches) {
       setEntered(true);
+      setSplashUp(false);
     }
   }, []);
 
@@ -49,6 +54,7 @@ export default function Home() {
         if (!entry.isIntersecting) {
           restoreScroll.current = Math.max(0, window.scrollY - el.offsetHeight);
           setEntered(true);
+          setSplashUp(false); // scrolled past: just unmount, no overlay fade needed
         }
       },
       { threshold: 0 },
@@ -85,6 +91,10 @@ export default function Home() {
   const enterFromButton = () => {
     restoreScroll.current = 0;
     setEntered(true);
+    setLeaving(true);
+    // Keep the splash mounted briefly as a fixed, fading overlay so it cross-fades
+    // into the revealed content instead of hard-cutting.
+    setTimeout(() => setSplashUp(false), 800);
   };
 
   return (
@@ -92,7 +102,7 @@ export default function Home() {
       <DynamicBackground nebulaPosition={nebulaPosition} visible={entered} />
       <Header floating visible={entered} />
 
-      {!entered && <HeroSplash sectionRef={splashRef} onEnter={enterFromButton} />}
+      {splashUp && <HeroSplash sectionRef={splashRef} onEnter={enterFromButton} leaving={leaving} />}
 
       <div id="main-content" className="z-10 w-full max-w-7xl mx-auto flex flex-col items-center pt-32 pb-10 px-4 text-center scroll-mt-28">
          <h1