fix: display swaps and contract calls correctly in tx history (closes #3)

- Preserve contract call metadata (direction, label, method) when token
  transfers merge with normal txs in fetchRecentTransactions
- Handle 'contract' direction in counterparty display for home and
  address detail list views
- Add decoded calldata display to transaction detail view, fetching
  raw input from Blockscout and using decodeCalldata from approval.js
- Show 'Unknown contract call' with raw hex for unrecognized calldata
- Export decodeCalldata from approval.js for reuse

src/popup/views/addressDetail.js

@@ -185,7 +185,10 @@ function renderTransactions(txs) {
     let html = "";
     let i = 0;
     for (const tx of txs) {
-        const counterparty = tx.direction === "sent" ? tx.to : tx.from;
+        const counterparty =
+            tx.direction === "sent" || tx.direction === "contract"
+                ? tx.to
+                : tx.from;
         const ensName = ensNameMap.get(counterparty) || null;
         const dirLabel = tx.directionLabel;
         const amountStr = tx.value