feat: add Rush Stack to sponsors (#64)

## PR Checklist

- [x] Steps in
[CONTRIBUTING.md](https://github.com/SquiggleTools/SquiggleConf.com/blob/main/.github/CONTRIBUTING.md)
were taken

## Overview

Adds Rush Stack linked to https://rushstack.io/?utm_source=squiggleconf
as a sponsor.

💖

Author: JoshuaKGoldberg

.astro/types.d.ts

@@ -1,2 +1 @@
 /// <reference types="astro/client" />
-/// <reference path="content.d.ts" />

src/assets/logos/rushstack-dark.svg

@@ -10,6 +10,8 @@ import mintlifyBlack from "~/assets/logos/mintlify-black.svg";
 import mintlifyWhite from "~/assets/logos/mintlify-white.svg";
 import progressGray from "~/assets/logos/progress-gray.svg";
 import progressWhite from "~/assets/logos/progress-white.svg";
+import rushStackDark from "~/assets/logos/rushstack-dark.svg";
+import rushStackLite from "~/assets/logos/rushstack-lite.svg";
 import voidZeroBlack from "~/assets/logos/voidzero-black.svg";
 import voidZeroWhite from "~/assets/logos/voidzero-white.svg";
 
@@ -59,6 +61,15 @@ export const sponsorsBySlug = {
 		placement: 1,
 		title: "Progress",
 	},
+	rushStack: {
+		href: "https://rushstack.io?utm_source=squiggleconf",
+		logos: {
+			dark: rushStackDark,
+			light: rushStackLite,
+		},
+		placement: 1,
+		title: "Rush Stack",
+	},
 	voidZero: {
 		href: "https://voidzero.dev?utm_source=squiggleconf",
 		logos: {