feat: add contract address display to AddressToken view

Show the ERC-20 contract address in a grey well below the token balance.
Full address displayed with click-to-copy and Etherscan link.

Also fix pre-existing prettier formatting in transactions.js.

Closes #9

src/popup/index.html

@@ -358,6 +358,23 @@
                     </div>
                 </div>
 
+                <!-- contract address well -->
+                <div
+                    id="address-token-contract-well"
+                    class="hidden bg-gray-200 p-2 mb-3 text-xs"
+                >
+                    <div class="text-muted mb-1">Contract Address</div>
+                    <div class="flex items-center">
+                        <span id="address-token-contract-dot"></span>
+                        <span
+                            id="address-token-contract-full"
+                            class="break-all underline decoration-dashed cursor-pointer"
+                            title="Click to copy"
+                        ></span>
+                        <span id="address-token-contract-etherscan-link"></span>
+                    </div>
+                </div>
+
                 <!-- actions -->
                 <div class="flex gap-2 mb-3">
                     <button