perf(compiler): reduce development build fingerprint overhead (#487)

- Parallelize compiler fingerprint reads while preserving cache identity and invalidation guarantees.
- Add a reproducible development build benchmark and regression coverage for file changes.

package.json

@@ -7,6 +7,7 @@
   "scripts": {
     "build": "pnpm -r --filter \"./packages/*\" run build",
     "build:fresh": "rm -rf packages/compiler/dist packages/cli/dist node_modules/.cache/scriptc-tsc && pnpm build",
+    "bench:builds": "node scripts/bench-builds.mjs",
     "test": "vitest run",
     "test:ts7": "node scripts/test-ts7.mjs",
     "test:fetch-conformance": "vitest run tests/harness/fetch-conformance.test.ts",