Upgrade to Vite 8 with Rolldown and switch to @vitejs/plugin-react v6

Replace Vite 6 (esbuild + Rollup) with Vite 8 (Rolldown), reducing
build times from ~12s to ~3.5s. Switch from the archived
@vitejs/plugin-react-swc to @vitejs/plugin-react v6 which uses Oxc
for React Refresh transforms.

package.json

@@ -128,7 +128,7 @@
     "@types/qrcode": "^1.5.5",
     "@types/react": "^18.3.1",
     "@types/react-dom": "^18.3.1",
-    "@vitejs/plugin-react-swc": "^3.5.0",
+    "@vitejs/plugin-react": "^6.0.1",
     "@webbtc/webln-types": "^3.0.0",
     "@webxdc/types": "^2.1.2",
     "autoprefixer": "^10.4.20",
@@ -141,7 +141,7 @@
     "tailwindcss": "^3.4.11",
     "typescript": "^5.5.3",
     "typescript-eslint": "^8.0.1",
-    "vite": "^6.3.5",
+    "vite": "^8.0.0",
     "vitest": "^3.1.4"
   }
 }

vite.config.ts

@@ -2,7 +2,7 @@ import { execSync } from "node:child_process";
 import fs from "node:fs";
 import path from "node:path";
 
-import react from "@vitejs/plugin-react-swc";
+import react from "@vitejs/plugin-react";
 import type { Plugin } from "vite";
 import { defineConfig } from "vitest/config";