Fix gunicorn logging in docker

[deepanshutiwari27]

Implemented the Docker Gunicorn logging fix for CollectOSS #374.
Root cause: Docker already relies on gunicorn_conf.py setting errorlog = '-', but both CLI startup paths passed --log-file, which overrides the config and sends Gunicorn errors only to the file. Docker then has nothing useful to show via docker logs.
Changes:
Added internal Gunicorn command builder: collectoss/application/cli/_gunicorn.py (line 17)
Updated backend startup to omit --log-file in Docker: collectoss/application/cli/backend.py (line 108)
Updated API startup the same way: collectoss/application/cli/api.py (line 65)
Switched Gunicorn config to the current Docker env name and kept errorlog = '-': collectoss/api/gunicorn_conf.py (line 45)
Added focused regression tests: tests/test_application/test_cli/test_gunicorn_command.py (line 7)

Fixes #374

[MoralCode]

is there a way to set gunicorn to log to both a file and dockers logs?

[MoralCode]

This is a change that was made in another PR already. can you rebase your PR on top of current main?

[MoralCode]

Can you explain why this was put in its own file/made into a function?

[deepanshutiwari27]

The Gunicorn command now requires deployment-specific logic (Docker vs non-Docker). Extracting it into build_gunicorn_command() centralizes command construction, makes the behavior testable, avoids duplicating Docker logging logic elsewhere, and keeps start() focused on process startup rather than command assembly.

[deepanshutiwari27]

Yes. Gunicorn can log to both a file and Docker's stdout/stderr, but not with a single --log-file option