fix: derive hasWallet from the wallet list on load (closes #195)

loadState() took hasWallet straight from storage, so any profile persisted
with the flag out of step with wallets stayed broken on every subsequent
load rather than only until the next write. The flag is now derived from
wallets.length at load time.

Deriving is only safe if no consumer wants hasWallet to mean something
other than "the wallet list is non-empty" -- an "onboarding was completed"
or "a wallet existed once" marker would be destroyed by it. So every
occurrence was enumerated at this base (git grep -n hasWallet over tracked
files; no bracket-notation, destructured or case-variant access exists).

Reads:

  src/popup/index.js:265 -- if (!state.hasWallet) gates the welcome view
  against the wallet list at popup init, immediately after loadState().
  Means "the user has a wallet"; the derivation is exactly that.

  src/popup/views/deleteWallet.js:73 -- if (!state.hasWallet) chooses the
  post-delete view. It reads the flag immediately after
  removeWalletFromState() has set it from state.wallets.length > 0, so it
  means "any wallets remain" -- identical to the derivation, and on the
  write path rather than the load path.

  src/shared/walletDelete.js:37,41,54 -- fallback address, selection reset
  and active-address reset inside removeWalletFromState(), all
  reads-after-write of the assignment at line 35
  (state.hasWallet = state.wallets.length > 0). Same expression, same
  invocation.

  src/shared/state.js:52 -- saveState() persists the in-memory value. With
  the derivation in place it now writes the derived value, so an
  inconsistent stored blob is normalized by the next ordinary save.

Writes: src/popup/views/addWallet.js:144,200,252 set it true immediately
after pushing a wallet; src/shared/walletDelete.js:35 sets it from the
remaining wallet count; src/shared/state.js:12 defaults it false alongside
wallets: []. Every writer keeps it equal to wallets.length > 0.

No consumer depends on the two disagreeing, so the derivation preserves
every read and needs no write-back on load.

tests/state.test.js

@@ -0,0 +1,104 @@
+const ADDRESS = "0x66133E8ea0f5D1d612D2502a968757D1048c214a";
+
+function oneWallet() {
+    return [{ name: "Wallet 1", type: "hd", addresses: [ADDRESS] }];
+}
+
+// state.js resolves the storage API at require time, so the stub has to exist
+// before the module is loaded, and the module registry has to be reset between
+// cases because `state` is a module-level singleton.
+function loadModuleWith(persisted) {
+    jest.resetModules();
+    const set = jest.fn(async () => {});
+    global.chrome = {
+        storage: {
+            local: {
+                get: jest.fn(async () =>
+                    persisted ? { autistmask: persisted } : {},
+                ),
+                set,
+            },
+        },
+    };
+    return { mod: require("../src/shared/state"), set };
+}
+
+afterEach(() => {
+    delete global.chrome;
+});
+
+describe("loadState hasWallet reconciliation", () => {
+    // A profile that deleted its last wallet on a build predating the write
+    // path fix keeps hasWallet: true forever. It must load as no wallet, which
+    // is what sends the popup to the welcome view.
+    test("stored hasWallet true with zero wallets loads as no wallet", async () => {
+        const { mod } = loadModuleWith({ hasWallet: true, wallets: [] });
+        await mod.loadState();
+        expect(mod.state.hasWallet).toBe(false);
+    });
+
+    test("stored hasWallet true with a missing wallets key loads as no wallet", async () => {
+        const { mod } = loadModuleWith({ hasWallet: true });
+        await mod.loadState();
+        expect(mod.state.wallets).toEqual([]);
+        expect(mod.state.hasWallet).toBe(false);
+    });
+
+    test("stored hasWallet false with one wallet loads as having a wallet", async () => {
+        const { mod } = loadModuleWith({
+            hasWallet: false,
+            wallets: oneWallet(),
+        });
+        await mod.loadState();
+        expect(mod.state.hasWallet).toBe(true);
+    });
+
+    test("absent hasWallet with wallets present loads as having a wallet", async () => {
+        const { mod } = loadModuleWith({ wallets: oneWallet() });
+        await mod.loadState();
+        expect(mod.state.hasWallet).toBe(true);
+    });
+
+    test("consistent stored states are preserved", async () => {
+        const withWallet = loadModuleWith({
+            hasWallet: true,
+            wallets: oneWallet(),
+        });
+        await withWallet.mod.loadState();
+        expect(withWallet.mod.state.hasWallet).toBe(true);
+
+        const without = loadModuleWith({ hasWallet: false, wallets: [] });
+        await without.mod.loadState();
+        expect(without.mod.state.hasWallet).toBe(false);
+    });
+
+    test("empty storage leaves the default no-wallet state", async () => {
+        const { mod } = loadModuleWith(null);
+        await mod.loadState();
+        expect(mod.state.hasWallet).toBe(false);
+        expect(mod.state.wallets).toEqual([]);
+    });
+
+    // The correction is derived on every load rather than written back, so a
+    // load never has a storage side effect.
+    test("loadState does not write to storage", async () => {
+        const { mod, set } = loadModuleWith({ hasWallet: true, wallets: [] });
+        await mod.loadState();
+        expect(set).not.toHaveBeenCalled();
+    });
+
+    // Deriving must not disturb the rest of the load.
+    test("other persisted fields still load", async () => {
+        const { mod } = loadModuleWith({
+            hasWallet: false,
+            wallets: oneWallet(),
+            networkId: "sepolia",
+            theme: "dark",
+            activeAddress: ADDRESS,
+        });
+        await mod.loadState();
+        expect(mod.state.networkId).toBe("sepolia");
+        expect(mod.state.theme).toBe("dark");
+        expect(mod.state.activeAddress).toBe(ADDRESS);
+    });
+});