Restore tuned nebula; make splash logo static for stable mobile LCP

- Revert the nebula density/parallax change that disturbed the carefully
  tuned streamer convergence (it gave no perf benefit; the nebula is behind
  the splash and not in the load trace).
- Logo is now fully static (no float/breath) so it's a stable LCP candidate
  on mobile; the rings, glow pulse, and staged button fade-ins still carry
  the motion. (Desktop TBT win from the framer->CSS conversion is retained.)

apps/web/src/components/landing/hero-splash.tsx

@@ -49,8 +49,8 @@ function SuchMark({ animate }: { animate: boolean }) {
           />
         </>
       )}
-      {/* letters with a gentle breath */}
-      <g className={animate ? "splash-breath" : undefined}>
+      {/* letters: static so they're a stable LCP candidate */}
+      <g>
         {/* S */}
         <path d="M 78,36 H 36 V 58 H 78 V 82 H 36" fill="none" stroke="#35c98e" strokeWidth="14" strokeLinecap="round" strokeLinejoin="round" />
         {/* U */}
@@ -137,7 +137,6 @@ export function HeroSplash({ onEnter, sectionRef }: { onEnter: () => void; secti
           style={{ animationDuration: "4.5s" }}
         />
         <motion.div
-          className={!entering && animate ? "splash-float" : undefined}
           style={{ filter: entering ? "url(#splash-water)" : undefined }}
           initial={{ opacity: 1, scale: 1 }}
           animate={entering ? { opacity: [1, 1, 0], scale: [1, 1.06, 1.14] } : undefined}

packages/ui/src/procedural/nebula-field.tsx

@@ -1,6 +1,6 @@
 'use client';
 
-import { motion, useAnimation } from "framer-motion";
+import { motion, useAnimation, useScroll, useTransform } from "framer-motion";
 import { useEffect, useState, useCallback, useMemo } from "react";
 import { cn } from "../lib/utils";
 import { Monitor } from "lucide-react";
@@ -79,12 +79,16 @@ const StreamLine = ({ d, themeMode, onHit, width, index }: StreamLineProps) => {
   );
 };
 
-export const NebulaField = ({ className, density = 4, themeMode = 'dark', position }: NebulaProps) => {
+export const NebulaField = ({ className, density = 8, themeMode = 'dark', position }: NebulaProps) => {
   // === ALL HOOKS MUST BE CALLED BEFORE ANY CONDITIONAL RETURNS ===
   const monitorControls = useAnimation();
   const [monitorColor, setMonitorColor] = useState(themeMode === 'light' ? "text-sky-500" : "text-cyan-400/70");
   const [prefersReducedMotion, setPrefersReducedMotion] = useState(false);
 
+  // Parallax Scroll hooks (called unconditionally)
+  const { scrollY } = useScroll();
+  const yRange = useTransform(scrollY, [0, 1000], [0, 250]);
+
   // Position calculations
   const computerX = position?.x ?? 18;
   const computerY = position?.y ?? 18;
@@ -187,7 +191,7 @@ export const NebulaField = ({ className, density = 4, themeMode = 'dark', positi
       {/* Slowly-pulsing Cherenkov "reactor pool" bloom */}
       <motion.div
         className="absolute h-[70vmax] w-[70vmax] -translate-x-1/2 -translate-y-1/2"
-        style={{ ...glowStyle, left: `${computerX}%`, top: `${computerY}%` }}
+        style={{ ...glowStyle, left: `${computerX}%`, top: `${computerY}%`, y: yRange }}
         initial={{ opacity: 0, scale: 0.85 }}
         animate={{ opacity: [0.55, 0.9, 0.55], scale: [0.95, 1.05, 0.95] }}
         transition={{ duration: 11, ease: "easeInOut", repeat: Infinity }}
@@ -203,7 +207,8 @@ export const NebulaField = ({ className, density = 4, themeMode = 'dark', positi
         transition={{ duration: 1.5 }}
         style={{ 
           left: `${computerX}%`, 
-          top: `${computerY}%`
+          top: `${computerY}%`,
+          y: yRange
         }}
       >
         <motion.div animate={monitorControls}>
@@ -217,10 +222,11 @@ export const NebulaField = ({ className, density = 4, themeMode = 'dark', positi
         </motion.div>
       </motion.div>
 
-      <svg
+      <motion.svg
         viewBox="0 0 100 100"
         preserveAspectRatio="none"
         className="w-full h-full opacity-50 dark:opacity-70 absolute inset-0"
+        style={{ y: yRange }} 
       >
         {paths.map((d: string, i: number) => (
           <StreamLine
@@ -232,7 +238,7 @@ export const NebulaField = ({ className, density = 4, themeMode = 'dark', positi
             index={i}
           />
         ))}
-      </svg>
+      </motion.svg>
     </div>
   );
 };