feat(ui): add video animation background

[ReenigneArcher]

Description

This PR adds an optional video background image.

Screenshot

Issues Fixed or Closed

• Closes Add video animation background #426

Type of Change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Dependency update (updates to dependencies)
• Documentation update (changes to documentation)
• Repository update (changes to repository files, e.g. .github/...)

Checklist

• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have added or updated the in code docstring/documentation-blocks for new or existing methods/components

Branch Updates

LizardByte requires that branches be up-to-date before merging. This means that after any PR is merged, this branch
must be updated before it can be merged. You must also
Allow edits from maintainers.

• I want maintainers to keep my branch updated

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (316505a) 73.94% compared to head (80b78a6) 74.03%.

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #427      +/-   ##
==========================================
+ Coverage   73.94%   74.03%   +0.08%     
==========================================
  Files          10       10              
  Lines         902      905       +3     
==========================================
+ Hits          667      670       +3     
  Misses        235      235              

Flag	Coverage Δ
Linux-x64	69.61% <100.00%> (+0.10%)	⬆️
Windows-x64	73.25% <100.00%> (+0.08%)	⬆️
Windows-x86	73.25% <100.00%> (+0.08%)	⬆️
macOS-x64	73.48% <100.00%> (+0.08%)	⬆️

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Files	Coverage Δ
pyra/config.py	84.09% <ø> (ø)
pyra/webapp.py	76.19% <100.00%> (+0.70%)	⬆️