fix: normalize container registry username to lowercase

[Guimove]

Docker registry names must be lowercase. This fix normalizes the username to lowercase before sending to the API, preventing the error: 'invalid tag ghcr.io/Guimove/...: repository name must be lowercase'

This applies to all registry types, not just GitHub Container Registry.

Summary

Issue:

Screenshots / Recordings

Testing

• Changes tested locally in the relevant Console's pages and Storybooks
• yarn test or yarn test -u (if you need to regenerate snapshots)
• yarn format
• yarn lint

PR Checklist

• I followed naming, styling, and TypeScript rules (see .cursor/rules)
• I performed a self-review (diff inspected, dead code removed)
• I titled the PR using Conventional Commits with a scope when possible (e.g. feat(service): add new Terraform service) - required for semantic-release
• I only kept necessary comments, written in English (watch for useless AI comments)
• I involved a designer to validate UI changes if I am not a designer
• I covered new business logic with tests (unit)
• I confirmed CI is green (Codecov red can be accepted)
• I reviewed and executed locally any AI-assisted code

[RemiBonnet]

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[codecov]

Codecov Report

❌ Patch coverage is 0% with 1 line in your changes missing coverage. Please review.
✅ Project coverage is 48.79%. Comparing base (8219801) to head (294ded4).

Files with missing lines	Patch %	Lines
...dit-modal/container-registry-create-edit-modal.tsx	0.00%	0 Missing and 1 partial ⚠️

Additional details and impacted files

@@             Coverage Diff             @@
##           staging    #2358      +/-   ##
===========================================
- Coverage    52.38%   48.79%   -3.60%     
===========================================
  Files          381      827     +446     
  Lines         7949    17267    +9318     
  Branches      2432     5133    +2701     
===========================================
+ Hits          4164     8425    +4261     
- Misses        3008     7255    +4247     
- Partials       777     1587     +810     

Flag	Coverage Δ
unittests	48.79% <0.00%> (-3.60%)	⬇️

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