fix(variables): improve empty state

[rmnbrd]

Summary

Issue:

This PR improves the empty state of the "External secrets" tab. We used to have a single "Add secret" button, but we were missing the "Add secret as file" option. This PR adds it.

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

[Copilot]

Pull request overview

This PR improves the “External secrets” tab UX by ensuring the empty state offers both creation paths (“Add secret as variable” and “Add secret as file”), aligning it with the non-empty state behavior.

Changes:

• Extracted an AddSecretDropdown component to reuse the “Add secret” dropdown UI.
• Updated the empty state to use the dropdown instead of a single “Add secret” button.
• Updated/added unit tests to select specific dropdown actions and assert the isFile modal prop.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 1 comment.

File	Description
libs/domains/variables/feature/src/lib/external-secrets/external-secrets-tab.tsx	Replaces empty state action button with a reusable “Add secret” dropdown component.
libs/domains/variables/feature/src/lib/external-secrets/external-secrets-tab.spec.tsx	Updates tests to interact with dropdown menu items and adds coverage for “Add secret as file” from empty state.

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 42.08%. Comparing base (fc50120) to head (e900482).

Additional details and impacted files

@@             Coverage Diff             @@
##           staging    #2740      +/-   ##
===========================================
- Coverage    45.74%   42.08%   -3.67%     
===========================================
  Files         1129      468     -661     
  Lines        24383    12566   -11817     
  Branches      7251     3913    -3338     
===========================================
- Hits         11154     5288    -5866     
+ Misses       11281     6264    -5017     
+ Partials      1948     1014     -934     

Flag	Coverage Δ
unittests	42.08% <100.00%> (-3.67%)	⬇️

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