docs: add ratings, devices, and analytics API endpoints

Phase 2 part 5: Split device management and analytics endpoints
- Ratings: get_ratings, create_rating (1-10 scale with half-stars)
- Devices: register_device, list_devices, get_devices, revoke_device
- Analytics: get_analytics (reading statistics)
- Include device registration flow details

docs/api/devices/list_devices.md

@@ -0,0 +1,48 @@
+# List User Devices
+
+Retrieve all devices registered to the current user.
+
+**Endpoint**: `GET /api/devices`
+**Auth**: Required
+
+## Request Headers
+
+| Header | Type | Required | Description |
+|--------|------|-----------|-------------|
+| Authorization | string | Yes | Bearer token |
+
+### Example Request
+
+```http
+GET /api/devices
+Authorization: Bearer eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9...
+```
+
+## Response (200 OK)
+
+```json
+{
+  "devices": [
+    {
+      "id": "uuid",
+      "device_name": "My Kobo Clara",
+      "device_type": "kobo",
+      "last_sync": "2026-01-31T10:00:00Z",
+      "last_seen": "2026-01-31T10:05:00Z",
+      "sync_enabled": true,
+      "auto_sync": true,
+      "sync_frequency_minutes": 5
+    }
+  ]
+}
+```
+
+## Error Responses
+
+| Code | Description |
+|------|-------------|
+| 401 | Invalid or expired token |
+
+## Try It Out
+
+<!-- API Explorer will be inserted here in Phase 3 -->