refactor(test): remove dotenvx and npm-run-all2 dependencies

- Replace dotenvx with direct env variable setting in test runner
- Update cover.mjs to use pnpm with inline env vars
- Run vitest directly for both regular and isolated tests
- Remove unused npm-run-all2 dependency
- Add NODE_COMPILE_CACHE, VITEST, and --max-semi-space-size=512
- Improves test startup time by eliminating wrapper process

All env vars from .env.test now set directly in spawnOptions.env

Author: jdalton

package.json

@@ -49,7 +49,6 @@
   "devDependencies": {
     "@babel/parser": "^7.28.5",
     "@biomejs/biome": "2.2.4",
-    "@dotenvx/dotenvx": "1.49.0",
     "@eslint/compat": "1.3.2",
     "@eslint/js": "9.35.0",
     "@socketsecurity/lib": "3.1.3",
@@ -71,7 +70,6 @@
     "globals": "16.4.0",
     "husky": "9.1.7",
     "magic-string": "^0.30.21",
-    "npm-run-all2": "8.0.4",
     "pacote": "21.0.1",
     "semver": "7.7.2",
     "taze": "19.6.0",