chore(tooling): port upstream infra/tooling audit fixes

Ports the kept-file portions of the upstream infra audit-fix subset onto
the clean-slate template branch (auth-only shape; workspaces feature never
existed here, so its package.json edit is skipped):

- resolve the root playwright config in pnpm test:visual (S8)
- prune dead VERCEL_ENV from turbo.json globalEnv (S9)
- drop the duplicate chromium install in the storybook CI job (S10)
- wire scripts/**/*.test.mjs under a dedicated vitest runner
  (vitest.scripts.config.mjs + pnpm test:scripts + CI validate step);
  convert node:test imports to vitest keeping node:assert
- ignore *.tsbuildinfo repo-wide and untrack the committed build state
- align every @trpc/* range on ^11.18.0 so the workspace resolves to a
  single version (peer-warning-free install)

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_016j8z4VHjedXDTjEDNg7qHK

.github/workflows/ci.yml

@@ -65,6 +65,10 @@ jobs:
       - run: pnpm typecheck
       - run: pnpm lint
       - run: pnpm conformance
+      # scripts/ is not a workspace package, so `pnpm test` (turbo) never
+      # reaches its test files — they get their own vitest run.
+      - name: Root scripts test suite
+        run: pnpm test:scripts
       - name: Compliance manifest drift check
         run: |
           pnpm compliance:emit-all --check || {
@@ -156,7 +160,5 @@ jobs:
       - name: Build Storybook
         run: pnpm --filter @repo/storybook build:storybook
       - run: pnpm test:stories
-      - name: Install Playwright browsers
-        run: pnpm exec playwright install chromium --with-deps
       - name: Visual regression
         run: pnpm test:visual