Update supporting files

[tieneupin]

• Add Ruff cache to the .gitignore file list.
• Introduce a .dockerignore file list to prevent copying of non-essential files when building Docker containers.
• Add an empty installers folder in repo for developers to store offline installers in when building Docker containers.
• Add logic to murfey-server Dockerfile to check for an IMOD installation file before attempting to download it.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 40.30%. Comparing base (02ec191) to head (cdd0aa9).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #712   +/-   ##
=======================================
  Coverage   40.30%   40.30%           
=======================================
  Files          99       99           
  Lines       11602    11602           
  Branches     1553     1553           
=======================================
  Hits         4676     4676           
  Misses       6708     6708           
  Partials      218      218           

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