feat: Sprint 1 — backend fondations TetaRdPG

Auth SuperOAuth (JWT validation + httpOnly cookie), entités users/characters/level_thresholds,
lazy calculation endurance, seed 100 niveaux, config prod-ready (trust proxy, helmet, CORS, rate limit).
Validé : health 200, auth flow, character CRUD, endurance lazy, 401 sans cookie.

src/database/data-source.ts

@@ -0,0 +1,14 @@
+import 'reflect-metadata';
+import { DataSource } from 'typeorm';
+import { User } from '../user/user.entity';
+import { Character } from '../character/entities/character.entity';
+import { LevelThreshold } from '../character/entities/level-threshold.entity';
+
+// DataSource pour le CLI TypeORM (migrations manuelles)
+export const AppDataSource = new DataSource({
+  type: 'postgres',
+  url: process.env.DATABASE_URL ?? 'postgresql://tetardpg:password@localhost:5432/tetardpg',
+  entities: [User, Character, LevelThreshold],
+  migrations: ['src/database/migrations/*.ts'],
+  synchronize: false,
+});