feat: update project structure and docs

docs/api/endpoints.md

@@ -0,0 +1,17 @@
+# API Endpoints
+
+## Overview
+
+| Method | Endpoint | Description |
+|--------|----------|-------------|
+| GET | `/` | Health check |
+
+## Health Check
+
+```http
+GET /
+```
+
+**Response:** `200 OK`
+
+Returns application status.

docs/api/index.md

@@ -0,0 +1,13 @@
+# API Reference
+
+This section contains auto-generated API documentation from source code docstrings.
+
+## Modules
+
+::: app.main
+    handler: python
+    options:
+      members:
+        - lifespan
+        - app_factory
+        - main