harden: list and end site connections made without Remember in Settings (closes #406)

A site allowed without "Remember" lives only in the background's
in-memory connectedSites map. Settings never listed it, and
AUTISTMASK_REMOVE_SITE, sent on every remove, did nothing, so the user
could not end such a connection.

Settings now asks the background for those sites and lists them under
Connected Sites. Removing a site from Allowed Sites or Connected Sites
drops its remembered entry under every address and sends
AUTISTMASK_REMOVE_SITE with the hostname; the background deletes every
matching connectedSites entry and sends accountsChanged with an empty
list to the site's tabs. Only the extension's own pages may send either
message.

Model: opus-5-5

src/background/index.js

@@ -1110,6 +1110,24 @@ async function broadcastAccountsChanged() {
     }
 }
 
+// Tell every open tab of a site Settings removed that it has no account.
+async function broadcastSiteRemoved(hostname) {
+    let tabs;
+    try {
+        tabs = await tabsQuery({});
+    } catch {
+        return;
+    }
+    for (const tab of tabs) {
+        if (!tab.url || extractHostname(tab.url) !== hostname) continue;
+        tabsSendMessage(tab.id, {
+            type: "AUTISTMASK_EVENT",
+            eventName: "accountsChanged",
+            data: [],
+        }).catch(() => {});
+    }
+}
+
 // Background balance refresh: every 60 seconds when the popup isn't open.
 // When the popup IS open, its 10-second interval keeps lastBalanceRefresh
 // fresh, so this naturally skips.
@@ -1306,6 +1324,8 @@ runtime.onMessage.addListener((msg, sender, sendResponse) => {
         "AUTISTMASK_TX_RESPONSE",
         "AUTISTMASK_SIGN_RESPONSE",
         "AUTISTMASK_ADDRESSES_REMOVED",
+        "AUTISTMASK_GET_CONNECTED_SITES",
+        "AUTISTMASK_REMOVE_SITE",
     ];
     if (POPUP_ONLY_TYPES.includes(msg.type) && !isExtensionSender(sender)) {
         sendResponse({ error: "Unauthorized sender" });
@@ -1662,8 +1682,28 @@ runtime.onMessage.addListener((msg, sender, sendResponse) => {
         return false;
     }
 
+    // Settings lists the sites connected without "Remember", which only this
+    // worker knows. The origin is what precedes the key's last colon.
+    if (msg.type === "AUTISTMASK_GET_CONNECTED_SITES") {
+        sendResponse(
+            Object.keys(connectedSites).map((key) =>
+                extractHostname(key.slice(0, key.lastIndexOf(":"))),
+            ),
+        );
+        return false;
+    }
+
+    // Settings removed this site and has already dropped its remembered
+    // entries. Its connections approved without "Remember" end here, under
+    // every address, and its open tabs are told it has no account.
     if (msg.type === "AUTISTMASK_REMOVE_SITE") {
-        // Popup already saved state; nothing else needed
+        for (const key of Object.keys(connectedSites)) {
+            const origin = key.slice(0, key.lastIndexOf(":"));
+            if (extractHostname(origin) === msg.hostname) {
+                delete connectedSites[key];
+            }
+        }
+        broadcastSiteRemoved(msg.hostname);
         return false;
     }
 });