feat!: faster loading of Boltz

[avik-pal]

• makes JLD2 a weak dependency
• removes deprecated functions
• use Lux.compute_output_size -- while this is not public, it is not going to be removed till v1.0 is released

[codecov]

Codecov Report

Attention: Patch coverage is 92.85714% with 1 line in your changes missing coverage. Please review.

Project coverage is 90.27%. Comparing base (930c0e3) to head (84ee1af).

Files	Patch %	Lines
src/initialize.jl	83.33%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main      #53      +/-   ##
==========================================
+ Coverage   90.04%   90.27%   +0.23%     
==========================================
  Files          25       24       -1     
  Lines         452      432      -20     
==========================================
- Hits          407      390      -17     
+ Misses         45       42       -3     

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