/drop dumps files that were added when Aider was launched

[ErykCh]

Issue

According to https://aider.chat/docs/conventions.html

I add the .aider.memory.md file with a description of what libraries are to be used and in which versions

however, this file is removed by the /drop command

it should be possible to add files rigidly, so that /drop doesn't throw them away

Version and model info

Aider v0.40.7-dev
Models: openrouter/anthropic/claude-3.5-sonnet with diff edit format, weak model openrouter/anthropic/claude-3-haiku
Git repo: .git with 36 files
Repo-map: using 2028 tokens
Added .aider.memory.md to the chat.