fill MASTG-KNOW-0105 user-initiated screenshot/recording placeholder

[simge-yigit]

This PR closes #3858

Description

Cover user-initiated capture paths (hardware shortcut, system screen) and the display flags that control capture behavior (FLAG_SECURE, SurfaceView.setSecure, SecureFlagPolicy, setRecentsScreenshotEnabled).

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[cpholguera]

Converting to draft until it really covers #3858

[simge-yigit]

For my initial contribution to MASTG-KNOW-0105, could you please let me know if it aligns with the repository's content guidelines? I would appreciate your feedback and opinion on it. Thank you.

[cpholguera]

Hi @simge-yigit , I've assigned @TheDauntless to review this and the other PR you opened. He'll soon give you feedback, thank you!