Implement ETH send and QR code receive

Send: stores mnemonic/private key with wallet data, derives
signing key from mnemonic + address index via ethers HDNodeWallet,
constructs transaction with parseEther, broadcasts via
sendTransaction, waits for confirmation, shows block number
and tx hash. ENS resolution in To field preserved.

Receive: QR code rendered to canvas via qrcode library (1.5.4).
Shows scannable QR above the full address text.

README updated with qrcode dependency and TODO progress.

src/popup/index.html

@@ -288,6 +288,9 @@
                     Share this address with the sender. Make sure you only use
                     this address to receive Ethereum tokens.
                 </p>
+                <div class="flex justify-center mb-3">
+                    <canvas id="receive-qr"></canvas>
+                </div>
                 <div
                     id="receive-address"
                     class="border border-border p-2 break-all select-all mb-3"

src/popup/index.js

@@ -5,8 +5,10 @@ const {
     Wallet,
     JsonRpcProvider,
     formatEther,
+    parseEther,
 } = require("ethers");
 const { getTopTokenPrices } = require("../shared/tokens");
+const QRCode = require("qrcode");
 
 const DEBUG = true;
 const DEBUG_MNEMONIC =
@@ -145,6 +147,22 @@ function formatUsd(amount) {
     );
 }
 
+// Get an ethers Wallet (signer) for the currently selected address
+function getSignerForCurrentAddress() {
+    const wallet = state.wallets[state.selectedWallet];
+    const addrIndex = state.selectedAddress;
+    if (wallet.type === "hd") {
+        const node = HDNodeWallet.fromPhrase(
+            wallet.mnemonic,
+            "",
+            BIP44_ETH_BASE,
+        );
+        return node.deriveChild(addrIndex);
+    } else {
+        return new Wallet(wallet.privateKey);
+    }
+}
+
 // -- balance fetching --
 function getProvider() {
     return new JsonRpcProvider(state.rpcUrl);
@@ -415,6 +433,7 @@ async function init() {
             type: "hd",
             name: "Wallet " + walletNum,
             xpub: xpub,
+            mnemonic: mnemonic,
             nextIndex: 1,
             addresses: [
                 { address: firstAddress, balance: "0.0000", tokens: [] },
@@ -444,6 +463,7 @@ async function init() {
         addWalletAndGoToMain({
             type: "key",
             name: "Wallet " + walletNum,
+            privateKey: key,
             addresses: [{ address: addr, balance: "0.0000", tokens: [] }],
         });
     });
@@ -485,7 +505,15 @@ async function init() {
 
     $("btn-receive").addEventListener("click", () => {
         const addr = currentAddress();
-        $("receive-address").textContent = addr ? addr.address : "";
+        const address = addr ? addr.address : "";
+        $("receive-address").textContent = address;
+        if (address) {
+            QRCode.toCanvas($("receive-qr"), address, {
+                width: 200,
+                margin: 2,
+                color: { dark: "#000000", light: "#ffffff" },
+            });
+        }
         showView("receive");
     });
 
@@ -530,13 +558,29 @@ async function init() {
                 return;
             }
         }
-        // TODO: prompt for password, decrypt key, construct and send transaction
-        const el = $("send-status");
-        el.textContent =
-            "Sending to " +
-            resolvedTo +
-            " (stub — password/signing not yet implemented)";
-        el.classList.remove("hidden");
+        const statusEl = $("send-status") || $("send-status");
+        statusEl.textContent = "Sending...";
+        statusEl.classList.remove("hidden");
+        try {
+            const signer = getSignerForCurrentAddress();
+            const provider = getProvider();
+            const connectedSigner = signer.connect(provider);
+            const tx = await connectedSigner.sendTransaction({
+                to: resolvedTo,
+                value: parseEther(amount),
+            });
+            statusEl.textContent = "Sent. Waiting for confirmation...";
+            const receipt = await tx.wait();
+            statusEl.textContent =
+                "Confirmed in block " +
+                receipt.blockNumber +
+                ". Tx: " +
+                receipt.hash;
+            // Refresh balance after send
+            refreshBalances().then(() => renderWalletList());
+        } catch (e) {
+            statusEl.textContent = "Failed: " + (e.shortMessage || e.message);
+        }
     });
 
     $("btn-send-back").addEventListener("click", () => {