fix(study-screen): streamline actions

[BrayanDSO]

Purpose / Description

Doing everything asynchronously and in parallel lead to some concurrency issues, like #19641

Fixes

• Fixes [New study screen] Card was modified error when tapping the answer buttons quickly #19641
• Closes fix(Reviewer): Prevent double auto-advance trigger when answering manually #20289

Approach

use executeAction as the single source of actions from the fragment

that way, most uses of launchCatchingIO got removed, so actions won't run parallelly

then use a mutex to make actions run in order inside executeAction

As executeAction is supposed to be used only by the View, not in the ViewModel internal logic, it being "synchronic" is alright, I think

How Has This Been Tested?

Emulator 31 + an auto clicker

Screen_recording_20260108_154243.mp4

Checklist

Please, go through these checks before submitting the PR.

• You have a descriptive commit message with a short title (first line, max 50 chars).
• You have commented your code, particularly in hard-to-understand areas
• You have performed a self-review of your own code
• UI changes: include screenshots of all affected screens (in particular showing any new or changed strings)
• UI Changes: You have tested your change using the Google Accessibility Scanner

[david-allison]

This doesn't look exception-safe.

The rest looks great!

[david-allison]

LGTM, cheers!

resolved