feat(iter-v2): T01 complete - security + infrastructure

- S1: .githooks/pre-commit blocks .env commits, .env.test in .gitignore
- S3: TOKEN_SECRET centralized to config/token.ts, all files import from it
- S3: checkTokenSecret enforces min 32-char TOKEN_SECRET at startup
- S5: Refresh Token mechanism (Access 2h + Refresh 30d, dual token)
- S5: POST /auth/refresh endpoint with rotation and max 5 per user
- S5: Frontend request.ts auto-refresh on 40101, concurrent-safe
- S6: Soft delete (deleted_at column), admin soft-delete with confirmName
- S6: POST /admin/users/:id/restore endpoint
- S6: All user queries filter deleted_at IS NULL
- S7: DB connection requires env vars, no fallback credentials
- Infra: jest.config.js, vitest.config.ts, .env.test
- Infra: node-cron, jest, ts-jest, supertest, vitest, @pinia/testing

server/src/routes/group.ts

@@ -246,7 +246,7 @@ router.get('/:id/members', async (req: AuthRequest, res: Response) => {
       `SELECT gm.user_id, gm.role, gm.created_at as joined_at,
               u.nickname, u.avatar_url
        FROM group_members gm
-       LEFT JOIN users u ON gm.user_id = u.id
+       LEFT JOIN users u ON gm.user_id = u.id AND u.deleted_at IS NULL
        WHERE gm.group_id = ?
        ORDER BY gm.role DESC, gm.created_at ASC`,
       [groupId]