fix: repair wallet state on delete (closes #156)

Deleting a wallet left three defects in the same path:

- `hasWallet` stayed true after the last wallet was deleted, so the next
  popup open rendered Home with "No wallets yet" instead of Welcome. It
  now tracks whether any wallet remains.
- The selection was reset to wallet 0 / address 0 unconditionally.
  `selectedWallet` now follows the splice (decremented when a wallet
  before it is removed), and only falls back to the first remaining
  wallet's first address when the selection itself was deleted;
  `activeAddress` only moves when it belonged to the deleted wallet.
- No `AUTISTMASK_ACTIVE_CHANGED` was sent, so connected sites kept
  reporting a deleted address. The delete path now broadcasts it after
  the state is persisted, whenever the active address actually changed,
  and the background re-emits `accountsChanged` from there.

The transition moved into `src/shared/walletDelete.js` so it can be
tested without a DOM. Site-permission cleanup is unchanged and still
covers every address of an HD wallet.

tests/walletDelete.test.js

@@ -0,0 +1,129 @@
+const {
+    removeWalletFromState,
+    broadcastActiveChanged,
+} = require("../src/shared/walletDelete");
+
+// Fixed addresses — never used for anything but these tests.
+const A0 = "0x66133E8ea0f5D1d612D2502a968757D1048c214a";
+const A1 = "0xdAC17F958D2ee523a2206206994597C13D831ec7";
+const B0 = "0x2260FAC5E5542a773Aa44fBCfeDf7C193bc2C599";
+const C0 = "0xA0b86991c6218b36c1d19D4a2e9Eb0cE3606eB48";
+
+function wallet(name, addresses) {
+    return {
+        name,
+        addresses: addresses.map((address) => ({ address })),
+    };
+}
+
+// A three-wallet state; wallet A is an HD wallet with two addresses.
+function makeState(overrides = {}) {
+    return {
+        hasWallet: true,
+        wallets: [wallet("A", [A0, A1]), wallet("B", [B0]), wallet("C", [C0])],
+        selectedWallet: 0,
+        selectedAddress: 0,
+        activeAddress: A0,
+        allowedSites: {
+            [A0]: ["a.example"],
+            [A1]: ["b.example"],
+            [B0]: ["c.example"],
+        },
+        deniedSites: { [A1]: ["d.example"], [C0]: ["e.example"] },
+        ...overrides,
+    };
+}
+
+describe("removeWalletFromState", () => {
+    test("deleting the last wallet clears hasWallet", () => {
+        const state = makeState({
+            wallets: [wallet("A", [A0])],
+            allowedSites: { [A0]: ["a.example"] },
+            deniedSites: {},
+        });
+
+        const { activeAddressChanged } = removeWalletFromState(state, 0);
+
+        expect(state.hasWallet).toBe(false);
+        expect(state.wallets).toEqual([]);
+        expect(state.selectedWallet).toBeNull();
+        expect(state.selectedAddress).toBeNull();
+        expect(state.activeAddress).toBeNull();
+        expect(activeAddressChanged).toBe(true);
+    });
+
+    test("deleting a non-selected wallet leaves the selection intact", () => {
+        const state = makeState({
+            selectedWallet: 2,
+            selectedAddress: 0,
+            activeAddress: C0,
+        });
+
+        const { activeAddressChanged } = removeWalletFromState(state, 1);
+
+        // Wallet C moved from index 2 to index 1 by the splice.
+        expect(state.wallets.map((w) => w.name)).toEqual(["A", "C"]);
+        expect(state.selectedWallet).toBe(1);
+        expect(state.selectedAddress).toBe(0);
+        expect(state.activeAddress).toBe(C0);
+        expect(activeAddressChanged).toBe(false);
+        expect(state.hasWallet).toBe(true);
+    });
+
+    test("deleting a wallet after the selection does not shift it", () => {
+        const state = makeState({
+            selectedWallet: 1,
+            selectedAddress: 0,
+            activeAddress: B0,
+        });
+
+        const { activeAddressChanged } = removeWalletFromState(state, 2);
+
+        expect(state.selectedWallet).toBe(1);
+        expect(state.activeAddress).toBe(B0);
+        expect(activeAddressChanged).toBe(false);
+    });
+
+    test("deleting the active wallet falls back to the first remaining address", () => {
+        const state = makeState({
+            selectedWallet: 0,
+            selectedAddress: 1,
+            activeAddress: A1,
+        });
+
+        const { activeAddressChanged } = removeWalletFromState(state, 0);
+
+        expect(state.wallets.map((w) => w.name)).toEqual(["B", "C"]);
+        expect(state.selectedWallet).toBe(0);
+        expect(state.selectedAddress).toBe(0);
+        expect(state.activeAddress).toBe(B0);
+        expect(activeAddressChanged).toBe(true);
+        expect(state.hasWallet).toBe(true);
+    });
+
+    test("site permissions are dropped for every address of the wallet", () => {
+        const state = makeState();
+
+        removeWalletFromState(state, 0);
+
+        expect(state.allowedSites).toEqual({ [B0]: ["c.example"] });
+        expect(state.deniedSites).toEqual({ [C0]: ["e.example"] });
+    });
+});
+
+describe("broadcastActiveChanged", () => {
+    afterEach(() => {
+        delete global.chrome;
+    });
+
+    test("sends AUTISTMASK_ACTIVE_CHANGED to the background", () => {
+        const sendMessage = jest.fn();
+        global.chrome = { runtime: { sendMessage } };
+
+        broadcastActiveChanged();
+
+        expect(sendMessage).toHaveBeenCalledWith({
+            type: "AUTISTMASK_ACTIVE_CHANGED",
+        });
+    });
+});