Persist navigation state across popup close/reopen

The current view, selected wallet, selected address, and selected
token are now saved to extension storage. When the popup reopens,
it restores to the last visited view instead of always returning
to the home screen.

Restorable views: main, address detail, address-token, receive,
settings. Non-restorable views (send, confirm, tx status, forms)
fall back to the nearest parent. Stored indices are validated
against current wallet data to handle stale references.

Also refactors receive view setup into a centralized receive.show()
function, eliminating duplicate QR/address/warning code from
addressDetail.js, addressToken.js, and home.js. Adds settings.show()
to centralize settings field population.

src/popup/views/addressToken.js

@@ -23,7 +23,6 @@ const {
 const { resolveEnsNames } = require("../../shared/ens");
 const { updateSendBalance, renderSendTokenSelect } = require("./send");
 const { log } = require("../../shared/log");
-const QRCode = require("qrcode");
 const makeBlockie = require("ethereum-blockies-base64");
 
 const EXT_ICON =
@@ -366,32 +365,7 @@ function init(ctx) {
     });
 
     $("btn-address-token-receive").addEventListener("click", () => {
-        const addr = currentAddress();
-        const address = addr ? addr.address : "";
-        $("receive-dot").innerHTML = address ? addressDotHtml(address) : "";
-        $("receive-address").textContent = address;
-        const addrLink = address ? etherscanAddressLink(address) : "";
-        $("receive-etherscan-link").innerHTML = addrLink
-            ? `<a href="${addrLink}" target="_blank" rel="noopener" class="inline-flex items-center">${EXT_ICON}</a>`
-            : "";
-        if (address) {
-            QRCode.toCanvas($("receive-qr"), address, {
-                width: 200,
-                margin: 2,
-                color: { dark: "#000000", light: "#ffffff" },
-            });
-        }
-        const warningEl = $("receive-erc20-warning");
-        if (state.selectedToken && state.selectedToken !== "ETH") {
-            warningEl.textContent =
-                "This is an ERC-20 token. Only send " +
-                currentSymbol +
-                " on the Ethereum network to this address. Sending tokens on other networks will result in permanent loss.";
-            warningEl.classList.remove("hidden");
-        } else {
-            warningEl.classList.add("hidden");
-        }
-        showView("receive");
+        ctx.showReceive();
     });
 }