[Data] Implement ConsentPreferences with DataStore

[LeGeRyChEeSe]

Description

Implement local persistence of user consent using Android DataStore (Preferences) to benefit from a reactive Flow-based API.

File to create

• app/src/main/java/com/vrhub/data/ConsentPreferences.kt

Specifications

• DataStore name: vrhub_settings
• Key: consent_enabled (boolean)
• Default value: false
• API:
  • val consentEnabled: Flow<Boolean>
  • suspend fun setConsentEnabled(enabled: Boolean)

Notes

• Do not use the existing SharedPreferences (Constants.PREFS_NAME) for this preference in order to benefit from Flow reactivity.
• Ensure the file is thread-safe and accessible from the main thread via suspend.

Reference

• docs/CLIENT_SPEC.md §5
• docs/CLIENT_IMPLEMENTATION.md §4