[WIP] Fix background flicker when toBack is true

[Codex]

Thanks for asking me to work on this. I will get started on it and keep this PR's description up to date as I form a plan and make progress.

---

This section details on the original issue you should resolve

<issue_title>bug: toBack: true makes background to flicker</issue_title>
<issue_description>## Bug Report

Capacitor Version

 Capacitor Doctor

Latest Dependencies:

  @capacitor/cli: 8.3.0
  @capacitor/core: 8.3.0
  @capacitor/android: 8.3.0
  @capacitor/ios: 8.3.0

Installed Dependencies:

  @capacitor/cli: 8.3.0
  @capacitor/core: 8.3.0
  @capacitor/ios: 8.3.0
  @capacitor/android: 8.3.0

[success] Android looking great! 👌

Plugin Version

│
▲   💊   Capgo Doctor  💊
│
●   App Name: test
│
●   App ID: test.app
│
●   App Version: 1.0.0
│
●   Web Dir: dist
│
●   OS: win32 Windows 11 IoT Enterprise LTSC 2024
│
●   Node: v24.14.1
│
●   Installed Dependencies:
│
●     @capgo/cli: 7.91.0
│
●     @capgo/camera-preview: 8.3.0
│
◇  Latest Dependencies:
│
●     @capgo/cli: 7.91.0
│
●     @capgo/camera-preview: 8.3.0
│
◆  ✅ All dependencies are up to date

context(s)

ManualModel: false
AutoMode: false
CapgoCloud: false
OnPremise: false

Platform(s)

Android 16, Google Pixel 9

Current Behavior

When CameraPreview.start() is called with toBack: true, the system status bar and bottom navigation bar flicker rapidly and change background colors. Setting toBack to false, makes the flicker go away.

Expected Behavior

System status bar and bottom navigation bar should not flicker with toBack: true.

Code Reproduction

I used Capacitor's template (pnpm create @capacitor/app@latest) and just added CameraPreview.start() to JS file.

https://github.com/dBaliukynas/capgo-camera-preview-bug

Other Technical Details

pnpm --version output: 10.33.0

node --version output: v24.14.1

pod --version output (iOS issues only):

Additional Context

capgo.mp4

</issue_description>

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[chatgpt-codex-connector]

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[chatgpt-codex-connector]

Restore system UI before returning on non-toBack start

This early return skips cleanup when a previous session already locked system bars for toBack=true. In a valid flow like start({ force: true, toBack: false }), the old session is stopped without calling stop(), so originalStatusBarColor/originalNavigationBarColor remain cached and the status/navigation bars stay forced to opaque colors (and contrast disabled on Android Q+) even though the new session is not toBack; this leaves the app UI in an incorrect state until a later explicit restore path runs.

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