fix: preserve multiple token transfers per tx hash for address-token view

A single transaction (e.g. a DEX swap) can produce multiple ERC-20
token transfers. The transaction merger was keyed by tx hash alone,
so only the last token transfer survived. This meant the address-token
view's contract-address filter often matched nothing.

Use a composite key (hash + contract address) so all token transfers
are preserved. Also remove the bare normal-tx entry when it gets
replaced by token transfers to avoid duplicates.

Closes #72

src/shared/transactions.js

@@ -153,9 +153,11 @@ 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.  A single transaction (e.g. a swap) can produce
+    // multiple token transfers (one per token involved), so we key token
+    // transfers by hash + contract address to keep all of them.  We also
+    // preserve contract-call metadata (direction, label, method) from the
+    // matching normal tx so swaps display correctly.
     for (const tt of ttJson.items || []) {
         const parsed = parseTokenTransfer(tt, addrLower);
         const existing = txsByHash.get(parsed.hash);
@@ -164,8 +166,13 @@ 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 doesn't appear as a
+            // duplicate with empty value; token transfers replace it.
+            txsByHash.delete(parsed.hash);
         }
-        txsByHash.set(parsed.hash, parsed);
+        // Use composite key so multiple token transfers per tx are kept.
+        const ttKey = parsed.hash + ":" + (parsed.contractAddress || "");
+        txsByHash.set(ttKey, parsed);
     }
 
     const txs = [...txsByHash.values()];