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/views/helpers.js

@@ -18,6 +18,7 @@ const VIEWS = [
     "receive",
     "add-token",
     "settings",
+    "transaction",
     "approve",
 ];