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/src/config.rs

@@ -6,6 +6,7 @@ pub struct AppConfig {
     pub database: DatabaseConfig,
     pub redis: RedisConfig,
     pub jwt: JwtConfig,
+    pub auth: AuthConfig,
     pub log: LogConfig,
 }
 
@@ -39,6 +40,11 @@ pub struct LogConfig {
     pub level: String,
 }
 
+#[derive(Debug, Clone, Deserialize)]
+pub struct AuthConfig {
+    pub super_admin_password: String,
+}
+
 impl AppConfig {
     pub fn load() -> anyhow::Result<Self> {
         let config = config::Config::builder()