perf: disable Sentry, remove grain overlay and shader gradient files

- Disable Sentry in all 3 configs (client/server/edge) - replayIntegration
  was recording every DOM mutation causing overhead in Chrome
- Remove grain-overlay div and its CSS (SVG feTurbulence + mix-blend-mode:overlay
  forces software compositing in Chrome on every frame)
- Remove mix-blend-multiply from BackgroundBlobs (prevents Chrome GPU compositing)
- Delete unused Grain.tsx, ShaderGradientBackground.tsx and its client wrapper

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

app/components/ShaderGradientBackground.tsx

@@ -1,112 +0,0 @@
-"use client";
-
-import React from "react";
-import { ShaderGradientCanvas, ShaderGradient } from "@shadergradient/react";
-
-const ShaderGradientBackground = () => {
-  return (
-    <div
-      style={{
-        position: "fixed",
-        top: 0,
-        left: 0,
-        width: "100%",
-        height: "100%",
-        zIndex: -1,
-        filter: "blur(150px)",
-        opacity: 0.65,
-        pointerEvents: "none",
-      }}
-    >
-      <ShaderGradientCanvas
-        style={{
-          position: "absolute",
-          top: 0,
-          left: 0,
-          width: "100%",
-          height: "100%",
-        }}
-      >
-        {/* Sphere 1 - Links oben */}
-        <ShaderGradient
-          control="props"
-          type="sphere"
-          animate="off"
-          brightness={1.3}
-          cAzimuthAngle={180}
-          cDistance={3.6}
-          cPolarAngle={90}
-          cameraZoom={1}
-          color1="#b01040"
-          color2="#b04a17"
-          color3="#e167c5"
-          positionX={-2.5}
-          positionY={1.5}
-          positionZ={0}
-          rotationX={0}
-          rotationY={15}
-          rotationZ={50}
-          uAmplitude={6.0}
-          uDensity={0.8}
-          uFrequency={5.5}
-          uSpeed={0.5}
-          uStrength={5.0}
-        />
-        
-        {/* Sphere 2 - Rechts mitte */}
-        <ShaderGradient
-          control="props"
-          type="sphere"
-          animate="off"
-          brightness={1.25}
-          cAzimuthAngle={180}
-          cDistance={3.6}
-          cPolarAngle={90}
-          cameraZoom={1}
-          color1="#e167c5"
-          color2="#b01040"
-          color3="#b04a17"
-          positionX={2.0}
-          positionY={-0.5}
-          positionZ={-0.5}
-          rotationX={0}
-          rotationY={25}
-          rotationZ={70}
-          uAmplitude={5.5}
-          uDensity={0.9}
-          uFrequency={4.8}
-          uSpeed={0.45}
-          uStrength={4.8}
-        />
-        
-        {/* Sphere 3 - Unten links */}
-        <ShaderGradient
-          control="props"
-          type="sphere"
-          animate="off"
-          brightness={1.2}
-          cAzimuthAngle={180}
-          cDistance={3.6}
-          cPolarAngle={90}
-          cameraZoom={1}
-          color1="#b04a17"
-          color2="#e167c5"
-          color3="#b01040"
-          positionX={-0.5}
-          positionY={-2.0}
-          positionZ={0.3}
-          rotationX={0}
-          rotationY={20}
-          rotationZ={60}
-          uAmplitude={5.8}
-          uDensity={0.7}
-          uFrequency={6.0}
-          uSpeed={0.52}
-          uStrength={4.9}
-        />
-      </ShaderGradientCanvas>
-    </div>
-  );
-};
-
-export default ShaderGradientBackground;