feat: add Cypress e2e tests for dashboard push actions

[fabiovincenzi]

Fixes #1390

• Add Cypress e2e tests for the admin UI dashboard's push management flows (approve, reject, cancel)
• Fix disabled prop not being forwarded in CustomButton component, which prevented the attestation confirm button
  from being properly disabled
• Add data-testid attributes to push detail action buttons and attestation dialog for reliable test selectors
• Add Cypress step to CI workflow alongside existing vitest e2e tests
• Make existing Cypress tests (repo.cy.js) compatible with Docker environment by replacing hardcoded URLs

[netlify]

✅ Deploy Preview for endearing-brigadeiros-63f9d0 canceled.

Name	Link
🔨 Latest commit	1234085
🔍 Latest deploy log	https://app.netlify.com/projects/endearing-brigadeiros-63f9d0/deploys/698ef9deae3d340008f208cd

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 81.25%. Comparing base (2351fa2) to head (1234085).
⚠️ Report is 2 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #1403   +/-   ##
=======================================
  Coverage   81.25%   81.25%           
=======================================
  Files          65       65           
  Lines        4657     4657           
  Branches      792      792           
=======================================
  Hits         3784     3784           
  Misses        858      858           
  Partials       15       15           

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