test: migrate from Mocha to Node native test runner with c8 coverage

Author: andrewshell

.mocharc.json

@@ -27,7 +27,8 @@
   },
   "scripts": {
     "build": "tsdown",
-    "test": "pnpm build && mocha",
+    "test": "pnpm build && c8 node --test test/*.test.cjs",
+    "coverage": "c8 report --reporter=text-lcov",
     "typecheck": "tsc --noEmit",
     "prepublishOnly": "pnpm build",
     "prepare": "husky"
@@ -50,8 +51,8 @@
     "@commitlint/cli": "^20.2.0",
     "@commitlint/config-conventional": "^20.2.0",
     "@types/node": "^25.0.0",
+    "c8": "^10.1.3",
     "husky": "^9.1.7",
-    "mocha": "^11.7.5",
     "mockdate": "^3.0.5",
     "safe-buffer": "^5.2.1",
     "seedrandom": "^3.0.5",