feat: simplify RBAC roles and remove dev role switcher

- Simplified RBAC system to two roles: super_admin and user.
- Removed tenant_admin and rp_admin roles across backend and frontend.
- Removed Dev Role Switcher feature from adminfront.
- Updated all handlers, middlewares, and navigation to reflect the new role model.
- Fixed backend build errors and updated tests.

backend/cmd/server/main.go

@@ -704,13 +704,9 @@ func main() {
 		AuthHandler:  authHandler,
 		KetoService:  ketoService,
 	})
-	requireAdmin := middleware.RequireRole(middleware.RBACConfig{
-		AllowedRoles: []string{domain.RoleSuperAdmin, domain.RoleTenantAdmin},
-		AuthHandler:  authHandler,
-		KetoService:  ketoService,
-	})
+	requireAdmin := requireSuperAdmin // Simplified: only super_admin can access admin management routes
 	requireAnyUser := middleware.RequireRole(middleware.RBACConfig{
-		AllowedRoles: []string{domain.RoleSuperAdmin, domain.RoleTenantAdmin, domain.RoleRPAdmin, domain.RoleUser},
+		AllowedRoles: []string{domain.RoleSuperAdmin, domain.RoleUser},
 		AuthHandler:  authHandler,
 		KetoService:  ketoService,
 	})