fix(browser): safely clean up IdsFile

[david-allison]

Note

Assisted-by: GPT-6

Purpose / Description

This is a special-case, where we modify the IdsFile inside the class as state, rather than just passing it as an argument, so it needs a little more delicate handling.

Fixes

• Part of [BUG] FileNotFoundException: /data/user/0/com.ichi2.anki/cache/multiselect-values... (IdsFile issue)  #19572

Approach

• Delete only after the replacement is written
• Delete the final snapshot via onPermanentDismissal

How Has This Been Tested?

Tests added

Checklist

• 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

[mikehardy]

Hey David 👋

Thanks for documenting why onCleared is the wrong cleanup hook here. I walked the CardBrowser save/restore path: the replacement IdsFile is written before the previous snapshot is deleted, and onPermanentDismissal only runs when isFinishing, so rotation / "Don't keep activities" still leave the file for restore. The tests pin that, including the missing-cacheDir write failure.

This is correctly Part of #19572 — process-death cache eviction can still ENOENT, and that path is still caught and silent-reported.

LGTM