Refactor navigation structure and API routes

- Centralize user menu, sidebar items, and breadcrumb logic.
- Map consistent API endpoints in `customerRoutes`.
- Replace inline route definitions with reusable constants.
- Refactor auth configuration file location.
- Improve `<Link>` usage to replace static `<a>` elements.
- Adjust sidebar and dropdown components to use dynamic navigation configurations.

internal_frontend/services/navigation/breadcrumb-utils.ts

@@ -0,0 +1,27 @@
+import {breadcrumbMap} from "@/lib/navigation/breadcrumb-map";
+
+export interface Breadcrumb {
+    href: string;
+    label: string;
+    isCurrentPage: boolean;
+}
+
+export function getBreadcrumbs(path: string): Breadcrumb[] {
+    const pathSegments = path.split('/').filter(Boolean);
+
+    return pathSegments.map((segment, index) => {
+        const href = `/${pathSegments.slice(0, index + 1).join('/')}`;
+        const label =
+            breadcrumbMap[segment.toLowerCase()] ||
+            segment
+                .split('-')
+                .map(word => word.charAt(0).toUpperCase() + word.slice(1))
+                .join(' ');
+
+        return {
+            label,
+            href,
+            isCurrentPage: index === pathSegments.length - 1,
+        };
+    });
+}