perf(images): convert remaining <img> tags to next/image project-wide

Clears every remaining @next/next/no-img-element warning — automatic
responsive srcset, lazy-loading, and format optimization instead of
always loading the original file at full size. Fixed-size icons got
explicit width/height; dynamic-aspect photos got fill inside a
relative wrapper.

app/components/Tools.tsx

@@ -1,4 +1,5 @@
 import Link from "next/link";
+import Image from "next/image";
 import { Reveal, RevealGroup, RevealItem } from "./Reveal";
 import { getWerkzeugeCards } from "../lib/payload";
 
@@ -38,8 +39,8 @@ export async function Tools() {
             className="md:col-span-4 flex gap-8 items-start rounded-md transition-transform duration-300 hover:-translate-y-1"
           >
             {/* Icon — uniform box, pre-flipped/rotated source asset */}
-            <div className="flex items-center justify-center shrink-0 size-14">
-              <img alt="" src={tool.icon} className="max-w-full max-h-full object-contain" />
+            <div className="relative flex items-center justify-center shrink-0 size-14">
+              <Image alt="" src={tool.icon} fill sizes="56px" className="object-contain" />
             </div>
 
             {/* Card content — self-stretch + h-full + justify-between so