chore: upgrade Vite 8.0.0-beta.18, Rolldown 1.0.0-rc.8 (#350)

Automated daily upgrade of Vite, Rolldown, and/or Vitest to the latest
available versions.

**Vite:** `8.0.0-beta.16` → `8.0.0-beta.18`
**Rolldown:** `1.0.0-rc.7` → `1.0.0-rc.8`

### Updated locations
- `packages/react-server/package.json` — `vite`, `rolldown`
- `test/package.json` — `vite`, `rolldown`, `vitest`, `@vitest/ui`
- `packages/rsc/package.json` — `vitest`, `@vitest/*`
- `packages/create-react-server/test/package.json` — `vitest`
- `package.json` — all `pnpm.overrides` for Vite
- `pnpm-lock.yaml`

### Smoke test
- Dev mode — `hello world` test passed ✅
- Build+start mode — `hello world` test passed ✅

Co-authored-by: lazarv <1749493+lazarv@users.noreply.github.com>

Author: react-server-bot[bot]

package.json

@@ -73,11 +73,11 @@
       "@uidotdev/usehooks>react-dom": "0.0.0-experimental-3bc2d414-20260304",
       "@vercel/analytics>react": "0.0.0-experimental-3bc2d414-20260304",
       "@vercel/speed-insights>react": "0.0.0-experimental-3bc2d414-20260304",
-      "vite": "8.0.0-beta.16",
-      "vite-plugin-inspect>vite": "8.0.0-beta.16",
-      "vite-plugin-svgr>vite": "8.0.0-beta.16",
-      "@vitejs/plugin-react>vite": "8.0.0-beta.16",
-      "@vitejs/plugin-react-swc>vite": "8.0.0-beta.16",
+      "vite": "8.0.0-beta.18",
+      "vite-plugin-inspect>vite": "8.0.0-beta.18",
+      "vite-plugin-svgr>vite": "8.0.0-beta.18",
+      "@vitejs/plugin-react>vite": "8.0.0-beta.18",
+      "@vitejs/plugin-react-swc>vite": "8.0.0-beta.18",
       "supertest>superagent": "9.0.2",
       "browserslist": "4.28.1",
       "caniuse-lite": "1.0.30001761"

packages/react-server/package.json

@@ -231,7 +231,7 @@
     "react-server-dom-webpack": "0.0.0-experimental-3bc2d414-20260304",
     "remark-frontmatter": "^5.0.0",
     "remark-mdx-frontmatter": "^4.0.0",
-    "rolldown": "1.0.0-rc.7",
+    "rolldown": "1.0.0-rc.8",
     "sass": "^1.86.0",
     "semver": "^7.6.3",
     "smol-toml": "^1.6.0",
@@ -242,7 +242,7 @@
     "strip-ansi": "^7.1.0",
     "style-to-js": "^1.1.12",
     "unstorage": "^1.16.0",
-    "vite": "8.0.0-beta.16",
+    "vite": "8.0.0-beta.18",
     "vite-plugin-inspect": "^11.3.3",
     "web-streams-polyfill": "^4.2.0",
     "zod": "^3.23.8"