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/instruction/utils/pumpfun.rs

@@ -154,6 +154,11 @@ pub mod accounts {
         };
 }
 
+/// Instruction discriminators for PumpFun program
+pub const BUY_DISCRIMINATOR: [u8; 8] = [102, 6, 61, 18, 1, 218, 235, 234];
+pub const BUY_EXACT_SOL_IN_DISCRIMINATOR: [u8; 8] = [56, 252, 116, 8, 158, 223, 205, 95];
+pub const SELL_DISCRIMINATOR: [u8; 8] = [51, 230, 133, 164, 1, 127, 131, 173];
+
 pub struct Symbol;
 
 impl Symbol {

src/instruction/utils/pumpswap.rs

@@ -136,6 +136,7 @@ pub mod accounts {
 }
 
 pub const BUY_DISCRIMINATOR: [u8; 8] = [102, 6, 61, 18, 1, 218, 235, 234];
+pub const BUY_EXACT_QUOTE_IN_DISCRIMINATOR: [u8; 8] = [198, 46, 21, 82, 180, 217, 232, 112];
 pub const SELL_DISCRIMINATOR: [u8; 8] = [51, 230, 133, 164, 1, 127, 131, 173];
 
 // Find a pool for a specific mint