feat: add SessionsModule with service for session management

Implemented SessionsModule and SessionsService to manage user sessions. Includes methods for session creation, refresh token rotation, and session revocation. Integrated with database and CryptoService for secure token handling.

backend/src/sessions/sessions.module.ts

@@ -0,0 +1,11 @@
+import { Module } from "@nestjs/common";
+import { CryptoModule } from "../crypto/crypto.module";
+import { DatabaseModule } from "../database/database.module";
+import { SessionsService } from "./sessions.service";
+
+@Module({
+	imports: [DatabaseModule, CryptoModule],
+	providers: [SessionsService],
+	exports: [SessionsService],
+})
+export class SessionsModule {}