Use ethers.js Mnemonic for real BIP-39 phrase generation

Replace stub wordlist with ethers.Mnemonic.fromEntropy() using
crypto.getRandomValues(). Add esbuild to bundle popup JS so it
can import ethers directly — no background messaging needed.
Each die click now generates a valid, random BIP-39 mnemonic.

src/popup/index.js

@@ -1,5 +1,5 @@
 // AutistMask popup UI — view management and event wiring
-// All wallet logic will live in background/; this file is purely UI.
+const { Mnemonic } = require("ethers");
 
 const VIEWS = [
     "lock",
@@ -70,153 +70,11 @@ function makeStubAddress() {
     };
 }
 
-// Stub wordlist for random phrase generation.
-// TODO: replace with real BIP-39 generation via background.
-const STUB_WORDLIST = [
-    "abandon",
-    "ability",
-    "able",
-    "about",
-    "above",
-    "absent",
-    "absorb",
-    "abstract",
-    "absurd",
-    "abuse",
-    "access",
-    "accident",
-    "account",
-    "accuse",
-    "achieve",
-    "acid",
-    "acoustic",
-    "acquire",
-    "across",
-    "act",
-    "action",
-    "actor",
-    "actual",
-    "adapt",
-    "add",
-    "addict",
-    "address",
-    "adjust",
-    "admit",
-    "adult",
-    "advance",
-    "advice",
-    "aerobic",
-    "affair",
-    "afford",
-    "afraid",
-    "again",
-    "age",
-    "agent",
-    "agree",
-    "ahead",
-    "aim",
-    "air",
-    "airport",
-    "aisle",
-    "alarm",
-    "album",
-    "alcohol",
-    "alert",
-    "alien",
-    "all",
-    "alley",
-    "allow",
-    "almost",
-    "alone",
-    "alpha",
-    "already",
-    "also",
-    "alter",
-    "always",
-    "amateur",
-    "amazing",
-    "among",
-    "amount",
-    "amused",
-    "analyst",
-    "anchor",
-    "ancient",
-    "anger",
-    "angle",
-    "angry",
-    "animal",
-    "ankle",
-    "announce",
-    "annual",
-    "another",
-    "answer",
-    "antenna",
-    "antique",
-    "anxiety",
-    "any",
-    "apart",
-    "apology",
-    "appear",
-    "apple",
-    "approve",
-    "april",
-    "arch",
-    "arctic",
-    "area",
-    "arena",
-    "argue",
-    "arm",
-    "armed",
-    "armor",
-    "army",
-    "around",
-    "arrange",
-    "arrest",
-    "arrive",
-    "arrow",
-    "art",
-    "artefact",
-    "artist",
-    "artwork",
-    "ask",
-    "aspect",
-    "assault",
-    "asset",
-    "assist",
-    "assume",
-    "asthma",
-    "athlete",
-    "atom",
-    "attack",
-    "attend",
-    "attitude",
-    "attract",
-    "auction",
-    "audit",
-    "august",
-    "aunt",
-    "author",
-    "auto",
-    "autumn",
-    "average",
-    "avocado",
-    "avoid",
-    "awake",
-    "aware",
-    "awesome",
-    "awful",
-    "awkward",
-    "axis",
-];
-
-function generateStubMnemonic() {
-    const phrase = [];
-    for (let i = 0; i < 12; i++) {
-        const bytes = new Uint32Array(1);
-        crypto.getRandomValues(bytes);
-        phrase.push(STUB_WORDLIST[bytes[0] % STUB_WORDLIST.length]);
-    }
-    return phrase.join(" ");
+function generateMnemonic() {
+    const wallet = Mnemonic.fromEntropy(
+        globalThis.crypto.getRandomValues(new Uint8Array(16)),
+    );
+    return wallet.phrase;
 }
 
 // -- render wallet list on main view --
@@ -409,7 +267,7 @@ function init() {
 
     // -- Add wallet (unified create/import) --
     $("btn-generate-phrase").addEventListener("click", () => {
-        const phrase = generateStubMnemonic();
+        const phrase = generateMnemonic();
         $("wallet-mnemonic").value = phrase;
         $("add-wallet-phrase-warning").classList.remove("hidden");
     });