feat: pass is_cashback_coin from events; PumpFun examples use sol-parser-sdk only

- PumpFunParams/BondingCurve: from_trade/from_dev_trade take is_cashback_coin parameter
- pumpfun_copy_trading and pumpfun_sniper_trading use sol-parser-sdk for gRPC, pass e.is_cashback_coin
- address_lookup/nonce_cache call sites updated; README EN/CN Cashback and example notes

Co-authored-by: Cursor <cursoragent@cursor.com>

src/common/bonding_curve.rs

@@ -65,6 +65,8 @@ pub struct BondingCurveAccount {
 }
 
 impl BondingCurveAccount {
+    /// When building from event/parser data (e.g. sol-parser-sdk), pass the token's cashback flag
+    /// so that sell instructions include the correct remaining accounts. From RPC use `from_mint_by_rpc` instead.
     pub fn from_dev_trade(
         bonding_curve: Pubkey,
         mint: &Pubkey,
@@ -72,6 +74,7 @@ impl BondingCurveAccount {
         dev_sol_amount: u64,
         creator: Pubkey,
         is_mayhem_mode: bool,
+        is_cashback_coin: bool,
     ) -> Self {
         let account = if bonding_curve != Pubkey::default() {
             bonding_curve
@@ -89,10 +92,12 @@ impl BondingCurveAccount {
             complete: false,
             creator: creator,
             is_mayhem_mode: is_mayhem_mode,
-            is_cashback_coin: false,
+            is_cashback_coin,
         }
     }
 
+    /// When building from event/parser data (e.g. sol-parser-sdk), pass the token's cashback flag
+    /// so that sell instructions include the correct remaining accounts. From RPC use `from_mint_by_rpc` instead.
     pub fn from_trade(
         bonding_curve: Pubkey,
         mint: Pubkey,
@@ -102,6 +107,7 @@ impl BondingCurveAccount {
         real_token_reserves: u64,
         real_sol_reserves: u64,
         is_mayhem_mode: bool,
+        is_cashback_coin: bool,
     ) -> Self {
         let account = if bonding_curve != Pubkey::default() {
             bonding_curve
@@ -119,7 +125,7 @@ impl BondingCurveAccount {
             complete: false,
             creator: creator,
             is_mayhem_mode: is_mayhem_mode,
-            is_cashback_coin: false,
+            is_cashback_coin,
         }
     }