Theme resets to default (white) when app switches to local connection over Wi‑Fi

**Environment**

App version: 2026.5.0
iOS version: (fill yours, e.g. iOS 18.x / 26.x)
Device: (e.g. iPhone 15 Pro)
HA Core version: (your version)
Theme: Dark

**Describe the bug**
When the Home Assistant iOS app switches from external connection (cellular/WAN) to a local connection (Wi‑Fi → internal URL), the selected theme is not applied and the UI falls back to the default white/light theme.
This happens even if:

A theme is explicitly selected in the user profile
The theme works correctly before network switching

**Steps to reproduce**

Configure both:

External URL (e.g. Nabu Casa / domain)
Internal URL (local IP or hostname)

Open the app on cellular network
Confirm the correct theme (e.g. dark/custom theme is active)
Enable Wi‑Fi and let the app switch to local connection
Observe UI after reload

**Possible root cause (hypothesis)**
During network switch:

App reloads WebView with internal URL
Frontend initialization is incomplete or delayed
Theme event is not applied
App falls back to default theme

A similar behavior is observed when opening the application: the loading screen is displayed in the (default settings) white with the selected design theme.