⚖️ fix: Add Configurable File Size Cap for Conversation Imports

[MarcAmick]

Pull Request Template

Summary

Implement a max size for conversations imports to prevent bringing down the application by uploading a large file. Also modified import endpoint such that if any error does occur, it bubbles the error up and the front end displays an error message. Before this fix, it returns a 200 and the front end says the import was successful when an error occurs.

Addresses issue: #10011

Change Type

• Bug fix (non-breaking change which fixes an issue)

Testing

Please describe your test process and include instructions so that we can reproduce your test. If there are any important variables for your testing configuration, list them here.

• tested manually that the CONVERSATION_IMPORT_MAX_FILE_SIZE_BYTES env file defaults to 0 which allows all files to be uploaded
• tested manually that the CONVERSATION_IMPORT_MAX_FILE_SIZE_BYTES when set to a number prevents a file from being uploaded in the front end code if it exceeds the number in bytes
• tested manually that the CONVERSATION_IMPORT_MAX_FILE_SIZE_BYTES will prevent the file from being parsed in the BACK END) if a file is uploaded that exceeds the number of bytes. This is of course to prevent malicious attempts of uploading a large file by bypassing the front end check

Test Configuration:

Checklist

Please delete any irrelevant options.

• My code adheres to this project's style guidelines
• I have performed a self-review of my own code
• I have commented in any complex areas of my code
• I have made pertinent documentation changes
• My changes do not introduce new warnings
• Local unit tests pass with my changes
• A pull request for updating the documentation has been submitted. (bugfix: Check file size of conversation being imported against a configured max to prevent large conversations imports from crashing librechat LibreChat-AI/librechat.ai#425)

[danny-avila]

Updated branch, resolved merge conflict, and removed all non-English localizations since they must be added through Locize:
https://www.librechat.ai/docs/translation#how-translations-work