harden: end a site's unremembered connection when its address or wallet is removed (closes #245)

A site connected without "Remember" lives only in the background's
in-memory connectedSites map. Removing an address or deleting a wallet
dropped the remembered permissions but never told the background; the
entry went only as a side effect of the accountsChanged broadcast, which
empties the whole map when the active address changes.

dropSitePermissions(), shared by both removal paths, now sends
AUTISTMASK_ADDRESSES_REMOVED with the removed addresses, and the
background deletes their entries. Only the extension's own pages may
send it.

Model: opus-5-5

tests/deleteWalletLostPassword.test.js

@@ -407,7 +407,9 @@ describe("deleting without the password", () => {
         expect(saved.activeAddress).toBe(A0);
         expect(saved.selectedWallet).toBe(0);
         expect(saved.selectedAddress).toBe(0);
-        expect(sent).toEqual([]);
+        expect(sent).toEqual([
+            { type: "AUTISTMASK_ADDRESSES_REMOVED", addresses: [B0] },
+        ]);
         // Settings is stubbed, so this is where the route hands over, not
         // where it renders.
         expect(mockSettingsShow).toHaveBeenCalled();
@@ -426,7 +428,10 @@ describe("deleting without the password", () => {
             "Wallet 3",
         ]);
         expect(saved.activeAddress).toBe(B0);
-        expect(sent).toEqual([{ type: "AUTISTMASK_ACTIVE_CHANGED" }]);
+        expect(sent).toEqual([
+            { type: "AUTISTMASK_ADDRESSES_REMOVED", addresses: [A0, A1] },
+            { type: "AUTISTMASK_ACTIVE_CHANGED" },
+        ]);
     });
 
     test("deleting the last wallet lands on Welcome with nothing left", async () => {