Show contract calls as "Approve USDT" instead of "0.0000 ETH"

Contract interactions (approve, swap, etc.) now display the method
name and token symbol instead of the meaningless 0 ETH value.
Blockscout provides the method name and whether the target is a
contract — parseTx uses these plus TOKEN_BY_ADDRESS to produce
labels like "Approve USDT" or "Swap LINK".

Added directionLabel field to parsed transactions so renderers
don't need to know about the sent/received/contract distinction.

Also: clicking a transaction on the home screen now opens the
transaction detail view instead of navigating to the address
detail view.

src/popup/views/home.js

@@ -134,8 +134,10 @@ function renderHomeTxList(ctx) {
     let i = 0;
     for (const tx of homeTxs) {
         const counterparty = tx.direction === "sent" ? tx.to : tx.from;
-        const dirLabel = tx.direction === "sent" ? "Sent" : "Received";
-        const amountStr = escapeHtml(tx.value + " " + tx.symbol);
+        const dirLabel = tx.directionLabel;
+        const amountStr = tx.value
+            ? escapeHtml(tx.value + " " + tx.symbol)
+            : escapeHtml(tx.symbol);
         const maxAddr = Math.max(10, 36 - Math.max(0, amountStr.length - 10));
         const displayAddr = truncateMiddle(counterparty, maxAddr);
         const addrStr = escapeHtml(displayAddr);
@@ -155,7 +157,7 @@ function renderHomeTxList(ctx) {
         row.addEventListener("click", () => {
             const idx = parseInt(row.dataset.tx, 10);
             const tx = homeTxs[idx];
-            // Find which wallet/address this tx belongs to and navigate
+            // Set selectedWallet/selectedAddress so back navigation works
             for (let wi = 0; wi < state.wallets.length; wi++) {
                 for (
                     let ai = 0;
@@ -169,7 +171,8 @@ function renderHomeTxList(ctx) {
                     ) {
                         state.selectedWallet = wi;
                         state.selectedAddress = ai;
-                        ctx.showAddressDetail();
+                        state.selectedToken = null;
+                        ctx.showTransactionDetail(tx);
                         return;
                     }
                 }