feat: add icon list generation script

this is used to validate icons for custom preferences. it generates both
typescript and c# code

Foxnouns.Frontend/icons.js

@@ -0,0 +1,42 @@
+// This script regenerates the list of icons for the frontend (Foxnouns.Frontend/src/lib/icons.ts)
+// and the backend (Foxnouns.Backend/Utils/BootstrapIcons.Icons.cs) from the currently installed version of Bootstrap Icons.
+// Run with `pnpm node icons.js` in the frontend directory.
+
+import { writeFileSync } from "fs";
+import icons from "bootstrap-icons/font/bootstrap-icons.json" with { type: "json" };
+
+const keys = Object.keys(icons);
+
+console.log(`Found ${keys.length} icons`);
+const output = JSON.stringify(keys);
+console.log(`Saving file as src/icons.ts`);
+
+writeFileSync(
+	"src/lib/icons.ts",
+	`// Generated code: DO NOT EDIT\n\nconst icons = ${output};\nexport default icons;`,
+);
+
+const csCode1 = `// <auto-generated />
+
+namespace Foxnouns.Backend.Utils;
+
+public static partial class BootstrapIcons
+{
+    private static readonly HashSet<string> Icons =
+    [
+`;
+
+const csCode2 = `    ];
+}
+`;
+
+let csOutput = csCode1;
+
+keys.forEach((element) => {
+	csOutput += `        "${element}",\n`;
+});
+
+csOutput += csCode2;
+
+console.log("Writing C# code");
+writeFileSync("../Foxnouns.Backend/Utils/BootstrapIcons.Icons.generated.cs", csOutput);