Polish: Make The Popup Follow the Active Tab Context (#33)

Currently the Popup only takes the opener page into account. Let's make
it follow pages, while switching. Should make it better to demo


https://github.com/user-attachments/assets/e65c1d8c-d052-4c97-9792-8bd0cd5ad31a

src/ui/browserAction/popupPage.js

@@ -52,8 +52,16 @@ export class BrowserActionPopup extends LitElement {
     super();
     this.pageURL = null;
     this._siteContext = null;
+    browser.tabs.onUpdated.addListener(() => this.updatePage());
+    browser.tabs.onActivated.addListener(() => this.updatePage());
+    vpnController.state.subscribe((s) => (this.vpnState = s));
+    this.updatePage();
+  }
+  updatePage() {
     Utils.getCurrentTab().then(async (tab) => {
       if (!Utils.isValidForProxySetting(tab.url)) {
+        this.pageURL = null;
+        this._siteContext = null;
         return;
       }
       const hostname = Utils.getFormattedHostname(tab.url);
@@ -62,8 +70,8 @@ export class BrowserActionPopup extends LitElement {
         this._siteContext = proxyHandler.siteContexts.value.get(this.pageURL);
       }
     });
-    vpnController.state.subscribe((s) => (this.vpnState = s));
   }
+
   connectedCallback() {
     super.connectedCallback();
   }