Fix calendar grid transparency overlapping issues

[GVodyanov]

Before	After

[codecov]

Codecov Report

Attention: Patch coverage is 0% with 16 lines in your changes missing coverage. Please review.

Project coverage is 22.91%. Comparing base (49f98be) to head (c49f211).
Report is 12 commits behind head on main.

Files with missing lines	Patch %	Lines
src/components/CalendarGrid.vue	0.00%	16 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff              @@
##               main    #6827      +/-   ##
============================================
- Coverage     22.95%   22.91%   -0.05%     
  Complexity      476      476              
============================================
  Files           252      252              
  Lines         12266    12290      +24     
  Branches       2362     2364       +2     
============================================
  Hits           2816     2816              
- Misses         9108     9132      +24     
  Partials        342      342              

Flag	Coverage Δ
javascript	14.56% <0.00%> (-0.04%)	⬇️
php	59.33% <ø> (ø)

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[ChristophWurst]

Wrong paste/button, sorry. The Darker parts are still weird for the events on the right. I'd expect past events to be equally transparent regardless of overlap or not

[GVodyanov]

Well, I made it work with some pretty weird geometry. I hope it isn't too hacky.

If anyone has a better idea than using the polygon clipping, that would be good though