Delete oldest read posts first

[louis-pre]

Context

• Read posts are limited to 500
• Once that limit is reached, 100 read posts are deleted
• The selection of the 100 read posts to delete is random because it is not ordered

This can cause an inconsistent experience for the user if the deletion happens to delete recently read posts. My opinion is that deleting the oldest read posts is the expected behavior.

Changes

• Add order by read time ascending to the selection query

[louis-pre]

@Docile-Alligator I believe this might be linked to some of the reports about raising the read posts limit. This change should improve the read posts experience without having to increase anything

[Docile-Alligator]

Thank you!