Add buy_exact_sol_in and buy_exact_quote_in instruction support

- Add BUY_EXACT_SOL_IN_DISCRIMINATOR for PumpFun
- Add BUY_EXACT_QUOTE_IN_DISCRIMINATOR for PumpSwap
- Add use_exact_in_instruction field to SwapParams
- When enabled, uses exact input instructions that spend exactly the
  specified SOL/quote amount with slippage applied to output tokens
- Defaults to false for backwards compatibility

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

src/trading/core/params.rs

@@ -67,6 +67,10 @@ pub struct SwapParams {
     pub fixed_output_amount: Option<u64>,
     pub gas_fee_strategy: GasFeeStrategy,
     pub simulate: bool,
+    /// Use exact input instructions (buy_exact_sol_in for PumpFun, buy_exact_quote_in for PumpSwap).
+    /// When true, the exact SOL/quote amount is spent and slippage is applied to output tokens.
+    /// When false (default), uses regular buy instruction where slippage is applied to SOL/quote input.
+    pub use_exact_in_instruction: bool,
 }
 
 impl std::fmt::Debug for SwapParams {