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.ts

@@ -1,10 +1,49 @@
-import { Injectable } from "@nestjs/common";
+import { Injectable, Logger, OnApplicationBootstrap } from "@nestjs/common";
 import { RbacRepository } from "./repositories/rbac.repository";
 
 @Injectable()
-export class RbacService {
+export class RbacService implements OnApplicationBootstrap {
+	private readonly logger = new Logger(RbacService.name);
+
 	constructor(private readonly rbacRepository: RbacRepository) {}
 
+	async onApplicationBootstrap() {
+		this.logger.log("RbacService initialized, checking roles...");
+		await this.seedRoles();
+	}
+
+	async seedRoles() {
+		try {
+			const count = await this.rbacRepository.countRoles();
+			if (count === 0) {
+				this.logger.log("No roles found, seeding default roles...");
+				const defaultRoles = [
+					{ name: "Administrator", slug: "admin", description: "Full system access" },
+					{
+						name: "Moderator",
+						slug: "moderator",
+						description: "Access to moderation tools",
+					},
+					{ name: "User", slug: "user", description: "Standard user access" },
+				];
+
+				for (const role of defaultRoles) {
+					await this.rbacRepository.createRole(
+						role.name,
+						role.slug,
+						role.description,
+					);
+					this.logger.log(`Created role: ${role.slug}`);
+				}
+				this.logger.log("Default roles seeded successfully.");
+			} else {
+				this.logger.log(`${count} roles already exist, skipping seeding.`);
+			}
+		} catch (error) {
+			this.logger.error("Error during roles seeding:", error);
+		}
+	}
+
 	async getUserRoles(userId: string) {
 		return this.rbacRepository.findRolesByUserId(userId);
 	}