docs: documenting modular architecture and testing infrastructure

README.md

@@ -62,6 +62,13 @@ To generate a clean production package and snapshot the current state:
 *   **Proxy:** Caddy (Docker) or local-ssl-proxy (Standalone/Dev).
 *   **AI Engine:** Google Gemini (Generative AI SDK).
 
+## 🧪 Testing & Verification (v1.10.0+)
+The project includes a comprehensive testing suite to ensure architectural stability:
+- **Backend:** `pytest` integration tests with in-memory database mocks.
+  - Run: `PYTHONPATH=. ./backend/venv/bin/pytest backend/tests/`
+- **Frontend:** `vitest` unit tests for custom React hooks and state logic.
+  - Run: `npm run test` (requires Node 20+)
+
 For more details, see [PROJECT_ARCHITECTURE.md](PROJECT_ARCHITECTURE.md).
 
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