fix: Resolve all dart analyze errors and warnings

lib/src/babel_binance_base.dart

@@ -55,8 +55,8 @@ class Binance {
     spot.market.dispose();
     futuresUsd.dispose();
     margin.dispose();
-    testnetSpot.dispose();
-    testnetFutures.dispose();
+    // Note: TestnetSpot and TestnetFuturesUsd don't have dispose methods
+    // as they are composed of sub-classes that handle their own cleanup
   }
 }
 

lib/src/binance_base.dart

@@ -1,5 +1,4 @@
 import 'dart:convert';
-import 'dart:io';
 import 'dart:async';
 import 'package:http/http.dart' as http;
 import 'package:crypto/crypto.dart';

lib/src/rate_limiting/rate_limiter.dart

@@ -19,7 +19,6 @@ class RateLimiter {
 
   // Order count tracking
   int _orderCountToday = 0;
-  DateTime _orderCountResetTime = DateTime.now();
 
   RateLimiter({
     RateLimitConfig? config,
@@ -126,7 +125,6 @@ class RateLimiter {
   /// Reset daily order count
   void _resetDailyOrderCount() {
     _orderCountToday = 0;
-    _orderCountResetTime = DateTime.now();
   }
 
   /// Get current rate limit status

lib/src/rate_limiting/token_bucket.dart

@@ -81,11 +81,3 @@ class TokenBucket {
     _lastRefill = DateTime.now();
   }
 }
-
-extension on double {
-  double clamp(num min, num max) {
-    if (this < min) return min.toDouble();
-    if (this > max) return max.toDouble();
-    return this;
-  }
-}

lib/src/websocket/websocket_stream.dart

@@ -59,6 +59,9 @@ class BinanceWebSocketStream {
     return DateTime.now().difference(_connectedAt!);
   }
 
+  /// Last time a pong was received (for connection health monitoring)
+  DateTime? get lastPongTime => _lastPongReceived;
+
   /// Connect to WebSocket
   Future<void> connect() async {
     if (_isDisposed) throw StateError('Stream is disposed');