Drop the isElectron flag from the API context

Only the Electron renderer ever set isElectron to true; the web entry passed
false. With that package gone the flag is constant, so remove it from
ApiCtxRoot, the context types and its consumers, together with the
pezkuwi.js.org link base it selected. In-browser account storage and the
WebUSB ledger option now follow the settings alone, as they already did on
the web.

Runtime environment detection (getEnvironment, ExternalWarning) reads the
user agent and is left as is.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>

packages/apps/src/Root.tsx

@@ -16,7 +16,6 @@ import BeforeApiInit from './overlays/BeforeInit.js';
 import Apps from './Apps.js';
 
 interface Props {
-  isElectron: boolean;
   store?: KeyringStore;
 }
 
@@ -29,7 +28,7 @@ function createTheme (settings: { uiTheme?: string }): ThemeDef {
   return { theme };
 }
 
-function Root ({ isElectron, store }: Props): React.ReactElement<Props> {
+function Root ({ store }: Props): React.ReactElement<Props> {
   const [theme, setTheme] = useState(() => createTheme(settings));
 
   useEffect((): void => {
@@ -45,7 +44,6 @@ function Root ({ isElectron, store }: Props): React.ReactElement<Props> {
           <ApiCtxRoot
             apiUrl={settings.apiUrl}
             beforeApiInit={<BeforeApiInit />}
-            isElectron={isElectron}
             store={store}
           >
             <KeyringCtxRoot>

packages/apps/src/index.tsx

@@ -21,5 +21,5 @@ if (!rootElement) {
 }
 
 createRoot(rootElement).render(
-  <Root isElectron={false} />
+  <Root />
 );