feat: Add EIP-712 signing for L1 authentication (src/auth.rs), HMAC-SHA256 for L2 API authentication, create_api_key(), derive_api_key(), create_or_derive_api_key(), Add set_api_creds() for credential management, Add create_order() and create_market_order() with EIP-712 signing, Add post_order() and create_and_post_order() for order submission, Add cancel(), cancel_orders(), cancel_all() for order management, Add OrderBuilder with proper tick size validation and rounding, Add get_orders() with filtering by ID, asset, market, Add get_trades() with filtering by time range, maker, asset, Add OpenOrderParams and TradeParams for query flexibility, Add balance_allowance() for balance and allowance queries, Add notifications() for push notification setup, Add get_midpoints() for efficient multi-token midpoint queries, Add get_prices() for batch bid/ask/mid price retrieval, Add BatchMidpointRequest/Response and BatchPriceRequest/Response types, Replace Decimal with u32 (Price) and i64 (Qty) on hot paths, Add decimal_to_price() and decimal_to_qty() conversion functions

src/utils.rs

@@ -128,7 +128,7 @@ pub mod crypto {
 pub mod math {
     use super::*;
     use rust_decimal::prelude::*;
-    use crate::types::{Price, Qty, SCALE_FACTOR, price_to_decimal, qty_to_decimal};
+    use crate::types::{Price, Qty, SCALE_FACTOR};
 
     // ========================================================================
     // LEGACY DECIMAL FUNCTIONS (for backward compatibility)
@@ -457,7 +457,6 @@ pub mod url {
 /// Rate limiting utilities
 pub mod rate_limit {
     use super::*;
-    use std::collections::VecDeque;
     use std::sync::{Arc, Mutex};
 
     /// Simple token bucket rate limiter