feat(auth): add tenant seed data and bootstrap logic

- seed.rs: creates 21 permissions, admin+viewer roles, admin user with Argon2 password
- AuthConfig added to server config with default password Admin@2026
- Server startup: auto-creates default tenant and seeds auth data if not exists
- Idempotent: checks for existing tenant before seeding

crates/erp-server/config/default.toml

@@ -15,5 +15,8 @@ secret = "change-me-in-production"
 access_token_ttl = "15m"
 refresh_token_ttl = "7d"
 
+[auth]
+super_admin_password = "Admin@2026"
+
 [log]
 level = "info"