Redesign transaction list and add transaction detail view

Transaction list entries are now two lines with more spacing:
- Line 1: humanized age (hover for ISO datetime) + direction (Sent/Received)
- Line 2: counterparty address + amount with symbol
- Clickable rows navigate to transaction detail view

Transaction detail view (placeholder) shows:
- Status, time, amount, from, to, transaction hash
- Back button returns to address detail

Also added "transaction" to VIEWS list in helpers.

src/popup/index.html

@@ -519,6 +519,41 @@
                 </div>
             </div>
 
+            <!-- ============ TRANSACTION DETAIL ============ -->
+            <div id="view-transaction" class="view hidden">
+                <button
+                    id="btn-tx-back"
+                    class="border border-border px-2 py-1 hover:bg-fg hover:text-bg cursor-pointer mb-2"
+                >
+                    &lt; Back
+                </button>
+                <h2 class="font-bold mb-2">Transaction</h2>
+                <div class="mb-2">
+                    <div class="text-xs text-muted">Status</div>
+                    <div id="tx-detail-status" class="text-xs"></div>
+                </div>
+                <div class="mb-2">
+                    <div class="text-xs text-muted">Time</div>
+                    <div id="tx-detail-time" class="text-xs"></div>
+                </div>
+                <div class="mb-2">
+                    <div class="text-xs text-muted">Amount</div>
+                    <div id="tx-detail-value" class="text-xs font-bold"></div>
+                </div>
+                <div class="mb-2">
+                    <div class="text-xs text-muted">From</div>
+                    <div id="tx-detail-from" class="text-xs break-all"></div>
+                </div>
+                <div class="mb-2">
+                    <div class="text-xs text-muted">To</div>
+                    <div id="tx-detail-to" class="text-xs break-all"></div>
+                </div>
+                <div class="mb-2">
+                    <div class="text-xs text-muted">Transaction hash</div>
+                    <div id="tx-detail-hash" class="text-xs break-all"></div>
+                </div>
+            </div>
+
             <!-- ============ APPROVAL ============ -->
             <div id="view-approve" class="view hidden">
                 <h2 class="font-bold mb-2">A website is requesting access</h2>