Fix P1 Rust clippy: unused variable _auth_ctx, _jwt_secret, derive Default for RouterBrain

products/01-llm-cost-router/src/auth/mod.rs

@@ -34,12 +34,12 @@ pub trait AuthProvider: Send + Sync {
 /// Local auth — bcrypt passwords + HS256 JWT (self-hosted mode)
 pub struct LocalAuthProvider {
     pool: sqlx::PgPool,
-    jwt_secret: String,
+    _jwt_secret: String,
     redis: deadpool_redis::Pool,
 }
 
 impl LocalAuthProvider {
-    pub fn new(pool: sqlx::PgPool, jwt_secret: String, redis: deadpool_redis::Pool) -> Self {
+    pub fn new(pool: sqlx::PgPool, _jwt_secret: String, redis: deadpool_redis::Pool) -> Self {
         Self { pool, jwt_secret, redis }
     }
 }