feat(shred): tx_index, Migrate without CPI, merge fix, doc limits

- Add tx_index to TransactionWithSlot (entry index), pass to parser
- Emit PumpFun Migrate even when no CPI (shred gets instruction-only)
- Merge: only overwrite Create/CreateV2 with CPI when value non-default
- Rename transaction_index -> tx_index across codebase
- Add docs/SHREDSTREAM_LIMITATIONS.md (ALT/CPI limits, field completeness)
- Comment shred path: static_account_keys only, no inner_instructions

Made-with: Cursor

src/streaming/common/event_processor.rs

@@ -66,7 +66,7 @@ pub async fn process_grpc_transaction(
             let signature = transaction_pretty.signature;
             let block_time = transaction_pretty.block_time;
             let recv_us = transaction_pretty.recv_us;
-            let transaction_index = transaction_pretty.transaction_index;
+            let tx_index = transaction_pretty.tx_index;
             let grpc_tx = transaction_pretty.grpc_tx;
 
             let adapter_callback = create_metrics_callback(callback.clone());
@@ -80,7 +80,7 @@ pub async fn process_grpc_transaction(
                 block_time,
                 recv_us,
                 bot_wallet,
-                transaction_index,
+                tx_index,
                 adapter_callback,
             )
             .await?;
@@ -121,6 +121,7 @@ pub async fn process_shred_transaction(
 
     let tx = transaction_with_slot.transaction;
     let slot = transaction_with_slot.slot;
+    let tx_index = transaction_with_slot.tx_index;
 
     if tx.signatures.is_empty() {
         return Ok(());
@@ -130,6 +131,8 @@ pub async fn process_shred_transaction(
     let recv_us = transaction_with_slot.recv_us;
 
     let adapter_callback = create_metrics_callback(callback);
+    // Shred 路径仅能拿到 static_account_keys，且无 inner_instructions，解析限制见 docs/SHREDSTREAM_LIMITATIONS.md
+    // 若交易使用 ALT，账户可能为 default/错误；无 CPI 合并，timestamp/reserves 等多为 0。
     let accounts = tx.message.static_account_keys();
 
     EventParser::parse_instruction_events_from_versioned_transaction(
@@ -138,12 +141,12 @@ pub async fn process_shred_transaction(
         &tx,
         signature,
         Some(slot),
-        None,
+        None, // shred 无 block_time
         recv_us,
         accounts,
         &[],
         bot_wallet,
-        None,
+        tx_index,
         adapter_callback,
     )
     .await?;