perf: increase test concurrency and add coverage to pre-commit hook

Add --test-concurrency=32 to all test scripts so timer-bound tests run
more files in parallel. Add pnpm test:coverage to the pre-commit hook
so the coverage gate is enforced locally before every commit.

Author: sharon77242

.husky/pre-commit

@@ -1 +1 @@
-pnpm run typecheck && pnpm run lint && pnpm run format:check && pnpm run build
+pnpm run typecheck && pnpm run lint && pnpm run format:check && pnpm run build && cd packages/agent && pnpm run test:coverage

packages/agent/package.json

@@ -38,9 +38,9 @@
     "lint:fix": "eslint . --fix",
     "format": "prettier --write .",
     "format:check": "prettier --check .",
-    "test": "node --test --experimental-strip-types tests/**/*.test.ts tests/*.test.ts",
-    "test:watch": "node --test --experimental-strip-types --watch tests/**/*.test.ts tests/*.test.ts",
-    "test:coverage": "node --test --experimental-test-coverage --test-coverage-lines=95 --test-coverage-functions=90 --test-coverage-branches=90 --experimental-strip-types tests/**/*.test.ts tests/*.test.ts",
+    "test": "node --test --test-concurrency=32 --experimental-strip-types tests/**/*.test.ts tests/*.test.ts",
+    "test:watch": "node --test --test-concurrency=32 --experimental-strip-types --watch tests/**/*.test.ts tests/*.test.ts",
+    "test:coverage": "node --test --test-concurrency=32 --experimental-test-coverage --test-coverage-lines=95 --test-coverage-functions=90 --test-coverage-branches=90 --experimental-strip-types tests/**/*.test.ts tests/*.test.ts",
     "validate": "pnpm run typecheck && pnpm run lint && pnpm run format:check && pnpm run test:coverage",
     "prepublishOnly": "node -e \"require('fs').copyFileSync('../../README.md','./README.md')\" && pnpm run build",
     "postpublish": "node -e \"require('fs').unlinkSync('./README.md')\""