Inteligent name template for saving unnanemed/noname attachments/parts

Checklist

• I have used the search function to see if someone else has already submitted the same feature request.
• I will describe the problem with as much detail as possible.
• This issue only contains a request for one single feature, not multiple (related) features.

App version

6.202

Problem you are trying to solve

Many emails have attachments with names like "noname.jpg" . When saving them k9mail will rename them to "nonameXXX.jpg" which works but may cause data loss because of conflicting name if attachments are synced between several devices and deleted locally.

Suggested solution

Make it possible to use an expandable template to save attachments, such as original-name+date_time or original-name_msgid

This should be much more robust against accidentally overwriting stored attachments/files.

Screenshots / Drawings / Technical details

No response

The issue does not name implementation files, tests, or entry points. Start by locating the attachment-saving flow and the logic that renames noname attachments, then review how filenames are currently made unique. Done means defining the supported expandable template behavior and ensuring saved attachments avoid unintended name collisions.