* Remove Gateway module, configuration, and references
* Update backend services to directly handle requests under `/api` prefix
* Adjust frontend contact route to connect directly to the server
* Centralize authentication logic and integrate token refresh mechanism
- Delete Gateway module, associated Spring Boot application, and related configuration (`GatewayApplication.java`, `application.yml`, and `pom.xml`).
- Remove Gateway references in `docker-compose.yml`, `.gitlab-ci.yml`, and `backend/pom.xml`.
- Update backend services to directly handle requests under `/api` prefix (e.g., `/api/customers`, `/api/contact`).
- Adjust frontend contact route to connect directly to the server, replacing gateway references with server URLs.
- Introduce `AuthWrapper` component for streamlined session-based layouts and authentication handling.
- Add new utilities (`tokenUtils.ts`) for JWT decoding, token expiration checks, and refresh operations via Keycloak.
- Refactor `serverCall` and `authOptions` to use centralized token refresh logic, removing redundant implementations.
- Implement `ClientSessionProvider` for consistent session management across the client application.
- Simplify `RootLayout` by delegating authentication enforcement to `AuthWrapper`.
- Add `resetForm` utility to restore initial modal state.
- Automatically reset form state when dialog closes or a new customer is created to improve UX.
- Decode and validate JWT payload to detect expired or near-expiring tokens.
- Implement `refreshAccessToken` using Keycloak endpoints for seamless token refresh.
- Modify `serverCall` to refresh and update token dynamically before API requests.
- Improve error logging for token decoding and refresh operations.
- Delete unused `callApi` utility and related imports across components.
- Replace `callApi` with direct `fetch` usage in `validateCustomer` and `addCustomer`.
- Update `customerRoutes` to include `/api` prefix for consistency.
- Refactor `useErrorHandler` to ensure comprehensive state management during errors.
- Improve `ErrorBoundary` component text for better clarity in fallback UI.
- Align `CustomersPage` logic with `useCallback` for optimized dependency management.
- Add `onCustomerCreated` callback to refresh customer list after creation.
- Integrate `showInfoToast` and `showSuccessToast` for validation and creation feedback.
- Prevent closing modal on backdrop click; add explicit cancel button.
- Refactor `addCustomer` to use `callApi` and centralized routes.
- Simplify customer fetching logic in `CustomersPage` with reusable function.
- Replace `showError` with a more versatile `showToast` utility.
- Add specific toast functions (`showErrorToast`, `showSuccessToast`, etc.) for better message handling.
- Remove `showError.ts` and migrate logic to `showToast.ts` for cleaner structure.
- Update `ErrorBoundary` and `useErrorHandler` to use the new `showToast` functions.
- Add `ErrorBoundary` component to handle rendering fallback UI during errors.
- Integrate `ErrorBoundary` into main layout and critical pages for global error handling.
- Create `useErrorHandler` hook to handle async errors consistently across components.
- Refactor `NewCustomerModal` and `CustomersPage` to leverage `useErrorHandler` for improved error management.
- Add a fallback dialog UI for user-friendly error reporting and resolution.
- Remove `CustomerRepository` and its methods for customer management and caching.
- Refactor customer-related pages (`[id]/page.tsx`, `customers/page.tsx`) to use direct `fetch` API calls.
- Update breadcrumb resolver to fetch data directly from the API.
- Simplify `addCustomer` use case to avoid repository dependency.
- Add in-memory caching for customer data in `CustomerRepository` to reduce API calls.
- Replace direct API calls with methods from `CustomerRepository`.
- Update customer-related pages (`[id]/page.tsx`, `customers/page.tsx`) to use `CustomerRepository` for data fetching.
- Adjust breadcrumb resolver to leverage `CustomerRepository`.
- Remove `axios` dependency from customer-related components.
