Align sent attachment previews with the composer

[hamzamerzic]

Summary

• render sent image attachments as the same 96×96 square crop used by the composer
• keep the matching corner radius while preserving full-image viewing on activation
• add regression guards that attachments remain above message text in both rendering paths

Testing

• focused attachment sizing and ordering tests (2 passed)
• npm run build
• visually verified the final sent attachment layout

[hamzamerzic]

Closing as superseded by #119. #119 contains the same sent-attachment preview behavior and additionally makes the preview button radius match the 14px image radius with explicit coverage. Keeping the stronger reviewed PR avoids landing the weaker visual duplicate.