Add host info views and network error handling

Introduce modular host info UI components: Header, InfoRow,
CopyButton, and Browser/Local/Public views. Refactor ServerInfo to
compose these components.

Add network error handling: background listens for webRequest
onErrorOccurred and forwards errors to Tab.handleError. Implement
Tab.handleError to store friendly error info and Tab.processSystemPage
to handle browser/system pages.

components/Browser.tsx

@@ -0,0 +1,32 @@
+import { CpuChipIcon, GlobeAltIcon } from '@heroicons/react/24/outline';
+import { Header } from './Header';
+import { InfoRow } from './Info';
+import type { HostInfo } from '@/utils/types';
+
+export const BrowserResourceView = ({ data }: { data: HostInfo }) => {
+  return (
+    <div className="w-80 bg-white dark:bg-gray-950 font-sans">
+      <Header
+        title="System Resource"
+        flagCode="unknown"
+      />
+      <div className="p-5">
+        <InfoRow
+          icon={CpuChipIcon}
+          label="Type"
+          value="Local Browser Page"
+          iconColor="text-orange-500"
+        />
+        <InfoRow
+          icon={GlobeAltIcon}
+          label="URL"
+          value={data.url}
+          iconColor="text-gray-400"
+        />
+      </div>
+      <div className="px-5 pb-5 text-xs text-gray-400 text-center">
+        This page is generated locally by your browser.
+      </div>
+    </div>
+  );
+};