major: Implement 3-tiered testing architecture

see [docs/testing.md](./docs/testing.md)

vitest.config.ts

@@ -0,0 +1,11 @@
+import { defineConfig } from "vitest/config";
+
+export default defineConfig({
+  test: {
+    exclude: [
+      "**/node_modules/**",
+      "**/dist/**",
+      "tests/evals/**"
+    ]
+  }
+});