feat(auth): implement role seeding on application bootstrap

- Added `onApplicationBootstrap` to seed default roles if none exist.
- Introduced `seedRoles` method to handle role creation with logging.
- Updated `RbacRepository` with `countRoles` and `createRole` methods.
- Added unit tests to ensure role seeding logic functions correctly.

backend/src/auth/rbac.service.spec.ts

@@ -9,6 +9,8 @@ describe("RbacService", () => {
 	const mockRbacRepository = {
 		findRolesByUserId: jest.fn(),
 		findPermissionsByUserId: jest.fn(),
+		countRoles: jest.fn(),
+		createRole: jest.fn(),
 	};
 
 	beforeEach(async () => {
@@ -58,4 +60,35 @@ describe("RbacService", () => {
 			expect(repository.findPermissionsByUserId).toHaveBeenCalledWith(userId);
 		});
 	});
+
+	describe("seedRoles", () => {
+		it("should be called on application bootstrap", async () => {
+			const seedRolesSpy = jest.spyOn(service, "seedRoles");
+			await service.onApplicationBootstrap();
+			expect(seedRolesSpy).toHaveBeenCalled();
+		});
+
+		it("should seed roles if none exist", async () => {
+			mockRbacRepository.countRoles.mockResolvedValue(0);
+
+			await service.seedRoles();
+
+			expect(repository.countRoles).toHaveBeenCalled();
+			expect(repository.createRole).toHaveBeenCalledTimes(3);
+			expect(repository.createRole).toHaveBeenCalledWith(
+				"Administrator",
+				"admin",
+				"Full system access",
+			);
+		});
+
+		it("should not seed roles if some already exist", async () => {
+			mockRbacRepository.countRoles.mockResolvedValue(3);
+
+			await service.seedRoles();
+
+			expect(repository.countRoles).toHaveBeenCalled();
+			expect(repository.createRole).not.toHaveBeenCalled();
+		});
+	});
 });