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/Info.tsx

@@ -0,0 +1,45 @@
+import { CopyButton } from './CopyButton';
+
+export const InfoRow = ({
+  icon: Icon,
+  label,
+  value,
+  href,
+  canCopy,
+  iconColor = "text-gray-400 dark:text-gray-500"
+}: {
+  icon: any,
+  label: string,
+  value: string | null,
+  href?: string,
+  canCopy?: boolean,
+  iconColor?: string
+}) => {
+  if (!value) return null;
+
+  return (
+    <div className="group flex items-start py-3 border-b border-gray-100 dark:border-gray-800 last:border-0">
+      <div className={`mt-0.5 mr-3 ${iconColor}`}>
+        <Icon className="w-4 h-4" />
+      </div>
+      <div className="flex-1 min-w-0">
+        <p className="text-[10px] uppercase tracking-wider text-gray-400 dark:text-gray-500 font-semibold mb-0.5">{label}</p>
+        <div className="flex items-center">
+          {href ? (
+            <a
+              href={href}
+              target="_blank"
+              rel="noreferrer"
+              className="text-sm font-medium text-gray-900 dark:text-gray-100 hover:text-blue-600 dark:hover:text-blue-400 truncate transition-colors flex items-center gap-1.5"
+            >
+              <span className="truncate">{value}</span>
+            </a>
+          ) : (
+            <span className="text-sm font-medium text-gray-900 dark:text-gray-100 truncate select-all">{value}</span>
+          )}
+          {canCopy && <CopyButton text={value} />}
+        </div>
+      </div>
+    </div>
+  );
+};