feat: add Kobo device sync support and fix device route protection

- Add Kobo sync handler with markup, bookmark, analytics, and initialization endpoints
- Add Kobo integration tests and Bruno API test collection
- Move device approve/reject routes from public to protected routes
- Enhance test infrastructure with DATABASE_URL support and helper functions
- Fix device GetDevice handler nil pointer handling
- Clean up test reports and session files

internal/handlers/devices.go

@@ -273,8 +273,12 @@ func (h *DeviceHandler) ListDevices(c echo.Context) error {
 }
 
 func (h *DeviceHandler) GetDevice(c echo.Context) error {
-	userID := c.Get("user_id").(string)
-	userUUID, err := uuid.Parse(userID)
+	userID := c.Get("user_id")
+	if userID == nil {
+		return c.JSON(http.StatusUnauthorized, map[string]string{"error": "unauthorized"})
+	}
+
+	userUUID, err := uuid.Parse(userID.(string))
 	if err != nil {
 		return c.JSON(http.StatusBadRequest, map[string]string{"error": "invalid user ID"})
 	}