refactor: Update GasFeeStrategy to instance-based API and update docs

docs/GAS_FEE_STRATEGY.md

@@ -13,12 +13,20 @@ This module supports users to configure strategies for SwqosType under different
 
 Each (SwqosType, TradeType) combination can only configure one strategy. Subsequent strategy configurations will override previous ones.
 
-### 2. Set Global Strategy (can also be configured individually)
+### 2. Create GasFeeStrategy Instance
+
+```rust
+use sol_trade_sdk::common::GasFeeStrategy;
+
+// Create a new GasFeeStrategy instance
+let gas_fee_strategy = GasFeeStrategy::new();
+```
+
+### 3. Set Global Strategy (can also be configured individually)
 
 ```rust
-use sol_trade_sdk::common::{gas_fee_strategy::GasFeeStrategy};
 // Set global strategy (normal strategy)
-GasFeeStrategy::set_global_fee_strategy(
+gas_fee_strategy.set_global_fee_strategy(
     150000, // cu_limit
     500000, // cu_price
     0.001,  // buy tip
@@ -26,24 +34,24 @@ GasFeeStrategy::set_global_fee_strategy(
 );
 ```
 
-### 3. Configuring Single Strategy
+### 4. Configuring Single Strategy
 
 ```rust
-// Configure normal strategy for SwqosType::Jito during Buy
-GasFeeStrategy::set_normal_fee_strategy(
+// Configure normal strategy for SwqosType::Jito
+gas_fee_strategy.set_normal_fee_strategy(
     SwqosType::Jito,
     xxxxx, // cu_limit
     xxxx,  // cu_price
     xxxxx, // buy_tip
-    xxxxx, // sell_tip
+    xxxxx  // sell_tip
 );
 ```
 
-### 4. Configuring High-Low Fee Strategy
+### 5. Configuring High-Low Fee Strategy
 
 ```rust
 // Configure high-low fee strategy for SwqosType::Jito during Buy
-GasFeeStrategy::set_high_low_fee_strategy(
+gas_fee_strategy.set_high_low_fee_strategy(
     SwqosType::Jito,
     TradeType::Buy,
     xxxxx, // cu_limit
@@ -54,15 +62,26 @@ GasFeeStrategy::set_high_low_fee_strategy(
 );
 ```
 
-### 5. Viewing and Cleanup
+### 6. Using in Trading Parameters
+
+```rust
+use sol_trade_sdk::TradeBuyParams;
+
+let buy_params = TradeBuyParams {
+    // ... other parameters
+    gas_fee_strategy: gas_fee_strategy.clone(),
+};
+```
+
+### 7. Viewing and Cleanup
 
 ```rust
 // Remove a specific strategy
-GasFeeStrategy::del(SwqosType::Jito, TradeType::Buy);
+gas_fee_strategy.del_all(SwqosType::Jito, TradeType::Buy);
 // View all strategies
-GasFeeStrategy::print_all_strategies();
+gas_fee_strategy.print_all_strategies();
 // Clear all strategies
-GasFeeStrategy::clear();
+gas_fee_strategy.clear();
 ```
 
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