fix: show decoded swap details on success-tx view (closes #63)

Carry decoded calldata info (action name, description, token details,
amounts, addresses) from the approval confirmation view through to the
success-tx view. For swap transactions, this now shows the same decoded
details (protocol, action, token symbols, amounts) that appeared on the
signing confirmation screen.

Changes:
- approval.js: store decoded calldata in pendingTxDetails.decoded
- txStatus.js: carry decoded through state.viewData, render in success view
- index.html: add success-tx-decoded container element

src/popup/index.html

@@ -531,6 +531,7 @@
             <!-- ============ TX SUCCESS ============ -->
             <div id="view-success-tx" class="view hidden">
                 <h2 class="font-bold mb-2">Transaction Confirmed</h2>
+                <div id="success-tx-decoded" class="mb-3 hidden text-xs"></div>
                 <div class="mb-3">
                     <div class="text-xs text-muted mb-1">Amount</div>
                     <div id="success-tx-summary" class="font-bold"></div>