conf 2026 website: Update conf homepage photos to 2025 (#2313)

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For your consideration, I have updated the photos used on the new Conf
2026 website. Here are some screenshots:

Kept the top image of a panel, but this is the AI panel from 2025

Dark mode
<img width="1329" height="1380" alt="Screenshot 2026-01-21 at 16 17 18"
src="https://github.com/user-attachments/assets/590e6e17-5943-4654-bbe4-89d32eb08f0d"
/>

Light mode
<img width="1328" height="1378" alt="Screenshot 2026-01-21 at 16 16 51"
src="https://github.com/user-attachments/assets/73ba3f0e-8ae2-437a-8c1b-05e3135f3153"
/>

Mobile view
<img width="438" height="940" alt="Screenshot 2026-01-21 at 16 18 33"
src="https://github.com/user-attachments/assets/be10625b-b35e-4a79-a22f-f07fb41395b1"
/>

Replaced the speaker image with one of the audience with hands up. If we
don't like this I can find another speaker image, but I think one
showing a crowded engaged audience is a good idea

<img width="1328" height="1379" alt="Screenshot 2026-01-21 at 16 17 33"
src="https://github.com/user-attachments/assets/8c5f1b48-e04b-49cc-a560-6330eb14d46b"
/>

<img width="1331" height="1383" alt="Screenshot 2026-01-21 at 16 17 52"
src="https://github.com/user-attachments/assets/ad7787ca-1211-4a7a-93d2-834f063e944d"
/>

This image is hidden in mobile view as before.

Author: jemgillam

src/app/conf/2026/components/hero/hero-image.tsx

@@ -1,6 +1,6 @@
 import Image from "next/image"
 
-import heroPhoto from "./hero-photo.jpeg"
+import heroPhoto from "./hero-photo.jpg"
 
 export function HeroImage() {
   return (
@@ -10,7 +10,7 @@ export function HeroImage() {
         placeholder="blur"
         width={1920}
         height={560}
-        alt="five speakers at GraphQLConf 2024"
+        alt="five speakers at GraphQLConf 2025"
         className="mx-auto h-[560px] w-[1920px] max-w-full object-cover"
       />
     </div>

src/app/conf/2026/components/hero/hero-photo.jpeg

@@ -4,7 +4,7 @@ import NextImage from "next/image"
 import { Button } from "../../../_design-system/button"
 import { GET_TICKETS_LINK } from "../../links"
 
-import speakerImage from "./speaker.webp"
+import speakerImage from "./audience.jpg"
 
 export interface RegisterTodayProps {
   className?: string
@@ -20,7 +20,7 @@ export function RegisterToday({ className }: RegisterTodayProps) {
     >
       <NextImage
         src={speakerImage}
-        alt="GraphQL Conference"
+        alt="GraphQL Conference audience"
         width="450"
         height="566"
         className="aspect-[312/392] w-full object-cover max-sm:hidden sm:aspect-[2] lg:aspect-[450/566] lg:h-[566px] lg:w-[450px]"