fix: preserve multiple token transfers per tx hash in transaction history

When a swap produces multiple ERC-20 token transfers with the same tx
hash (e.g. send WETH + receive USDC), only the last transfer was kept
because txsByHash was keyed by bare tx hash. This caused the
address-token view to show no transactions for tokens obtained via swap.

Use a composite key (hash:contractAddress) so all token transfers are
preserved. The bare-hash normal-tx entry is removed when token transfers
replace it to avoid duplication.

Closes #72

src/shared/transactions.js

@@ -153,9 +153,14 @@ async function fetchRecentTransactions(address, blockscoutUrl, count = 25) {
 
     // When a token transfer shares a hash with a normal tx, the normal tx
     // is the contract call (0 ETH) and the token transfer has the real
-    // amount and symbol. Replace the normal tx with the token transfer,
-    // but preserve contract call metadata (direction, label, method) so
-    // swaps and other contract interactions display correctly.
+    // amount and symbol. Preserve contract call metadata (direction, label,
+    // method) so swaps and other contract interactions display correctly.
+    //
+    // A single tx hash can produce multiple token transfers (e.g. a swap
+    // sends token A and receives token B). Use a composite key
+    // (hash:contractAddress) so every transfer is preserved. The original
+    // normal-tx entry (keyed by bare hash) is removed when at least one
+    // token transfer replaces it.
     for (const tt of ttJson.items || []) {
         const parsed = parseTokenTransfer(tt, addrLower);
         const existing = txsByHash.get(parsed.hash);
@@ -164,8 +169,12 @@ async function fetchRecentTransactions(address, blockscoutUrl, count = 25) {
             parsed.directionLabel = existing.directionLabel;
             parsed.isContractCall = true;
             parsed.method = existing.method;
+            // Remove the bare-hash normal tx so it isn't duplicated
+            txsByHash.delete(parsed.hash);
         }
-        txsByHash.set(parsed.hash, parsed);
+        // Use composite key so multiple token transfers per tx are kept
+        const compositeKey = parsed.hash + ":" + (parsed.contractAddress || "");
+        txsByHash.set(compositeKey, parsed);
     }
 
     const txs = [...txsByHash.values()];