🔒 [security fix] Use immutable PendingIntent without redundant update flag

[LeanBitLab]

🎯 What: Removed the redundant FLAG_UPDATE_CURRENT from PendingIntent creations in AwidgetProvider.kt.
⚠️ Risk: Using FLAG_UPDATE_CURRENT when not needed is a minor security concern; specifying only FLAG_IMMUTABLE is the preferred best practice for Android 12+ (API 31+) to reduce the attack surface of PendingIntents.
🛡️ Solution: Updated all 14 occurrences in AwidgetProvider.kt to use only FLAG_IMMUTABLE, as none of these intents (alarms, widget clicks, settings shortcuts) rely on updating extras after the PendingIntent is first created.

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PR created automatically by Jules for task 8744115456617007643 started by @LeanBitLab

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