[Bugfix] UnicodeEncodeError in backend_api.py on Windows (cp1252)

[gugabendin]

Bug description
I encountered a UnicodeEncodeError when uploading a file containing special characters (e.g., \u02dd) while running the GUI on Windows.

Windows defaults to cp1252 encoding, which causes a crash when writing non-standard characters to the .md or .txt files in the upload_files function.

Traceback

File "...\g4f\gui\server\backend_api.py", line 444, in upload_files
    f.write(f"{result}\n")
File "encodings\cp1252.py", line 19, in encode
UnicodeEncodeError: 'charmap' codec can't encode character '\u02dd'...

The Fix I fixed this by enforcing utf-8 encoding when opening files for writing in g4f/gui/server/backend_api.py.

In backend_api.py, inside the upload_files function:

Change 1 (approx line 432):
# Before
with open(os.path.join(bucket_dir, f"{filename}.md"), 'w') as f:

# After (Fix)
with open(os.path.join(bucket_dir, f"{filename}.md"), 'w', encoding="utf-8") as f:

Change 2 (approx line 461):
# Before
with open(os.path.join(bucket_dir, "files.txt"), 'w') as f:

# After (Fix)
with open(os.path.join(bucket_dir, "files.txt"), 'w', encoding="utf-8") as f:

This ensures compatibility with special characters on Windows systems.

[hlohaus]

@gugabendin, I have incorporated the encoding parameter into the open file calls within the main branch.

[github-actions]

Bumping this issue because it has been open for 7 days with no activity. Closing automatically in 7 days unless it becomes active again.