File Referencing with "@"

I sometimeneed to reference the same file across multiple chats or within a single chat over time, currently requiring repeated uploads.

Solution: Implement an "@" referencing system for uploaded files, similar to file referencing in code editors like Zed.

How it could work:

1. Type "@" in the chat input

2. A popover appears, showing:

   • Files previously uploaded in the current chat

   • Recently uploaded files (from any chat)

   • A search bar to search all files

3. Users can:

   • Continue typing after "@" to filter the suggested files

   • Use the search bar to filter files

   • Select a file from the popover using their mouse or keyboard

4. Upon selection, the content of the referenced file is sent to the LLM as if it were directly uploaded, eliminating the need for re-uploading.