feat: Add Copier Dashboard

[PaulKMueller (PaulKMueller)]

Changes

Depends on the frontend infrastructure PR #24.

• Adds aggregation of copier answers, template versions, and validation results.
• Adds the interactive Copier Dashboard with filtering, selectable columns, charts, copy controls, and shareable URL state.
• Includes a GitHub Pages workflow example and hosting documentation.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 100.00%. Comparing base (67d4c14) to head (a85708f).

Additional details and impacted files

@@                    Coverage Diff                     @@
##           frontend-infrastructure       #25    +/-   ##
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  Coverage                   100.00%   100.00%            
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  Files                           50        52     +2     
  Lines                         3122      3296   +174     
==========================================================
+ Hits                          3122      3296   +174     

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[Janina Wibker (JaninaWibkerQC)]

The amount of code that deals with error handling and fallbacks is sprinkled in everywhere instead of it being done in a few limited places and giving you confidence about types and especially truthyness of values.

Much of the code feels overly defensive as if the type system isn't doing its job.
I suspect that error handling placed in a few sensible locations could increase this confidence by quite a lot

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Similarly the logic for applying filters and transforming data from one thing to another seems to spread everywhere.
Each and every component has multiple helper functions, does a few operations itself, and just overall deals with data transformations way too much.
This can likely be fixed by properly thinking about what types should be used where, creating a few really useful helper functions and then reusing them.

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There are many places where I'd suggest splitting things out into seperate reusable components.
Many components seem to concern themselves with quite a lot of different things that you'd usually split up. You can also use react hooks to separate out stuff from the function body of a component

[Janina Wibker (JaninaWibkerQC)]

use .filter

[Janina Wibker (JaninaWibkerQC)]

This file and a few others contain an insane number of .map, .filter, new Map(), and new Set() calls.

I can't imagine that all of that is needed. I suspect with a good and thorough look you can remove about 1/2 of all this complexity