verify: Confirm gemspec required_ruby_version format consistency (WA-VERIFY-080)

[kitcommerce]

Summary

Confirms and fixes required_ruby_version format consistency across all Workarea gemspecs.

WA-VERIFY-073 (PR #1050) aligned the constraint value to >= 2.7.0, < 3.5.0 but wrote it in array form. This PR normalizes all gemspecs to the canonical single-string form.

Findings

Gemspec	Before (array form)	After (single-string form)	Status
core/workarea-core.gemspec	['>= 2.7.0', '< 3.5.0']	'>= 2.7.0, < 3.5.0'	✅ Fixed
admin/workarea-admin.gemspec	['>= 2.7.0', '< 3.5.0']	'>= 2.7.0, < 3.5.0'	✅ Fixed
storefront/workarea-storefront.gemspec	['>= 2.7.0', '< 3.5.0']	'>= 2.7.0, < 3.5.0'	✅ Fixed
testing/workarea-testing.gemspec	['>= 2.7.0', '< 3.5.0']	'>= 2.7.0, < 3.5.0'	✅ Fixed
workarea.gemspec	['>= 2.7.0', '< 3.5.0']	'>= 2.7.0, < 3.5.0'	✅ Fixed

Both forms are semantically equivalent in RubyGems; single-string is the canonical convention for gemspec constraints.

Audit notes: notes/gemspec-ruby-version-format-verify-2026-03-17.md

Client Impact

None. This is a cosmetic normalization only — the constraint value is unchanged. RubyGems treats both array and single-string forms identically at install time.

Fixes #1062

[kitcommerce]

Wave 1 Review Results

architecture: PASS — simple formatting normalization across gemspecs; no behavior change intended.
simplicity: PASS — straightforward change plus a helpful audit note.
security: PASS — no new trust boundaries introduced.
rails-conventions: PASS — uses canonical gemspec version constraint string format.

Wave 1 PASSED. Ready for Wave 2 / maintainers to merge when convenient.

[kitcommerce]

Wave 2 review (7x) — looks good; no behavior change expected.

{"reviewer":"test-quality","verdict":"PASS","severity":null,"summary":"Pure gemspec metadata normalization; no tests necessary beyond existing CI. ","findings":[]}

{"reviewer":"architecture","verdict":"PASS","severity":null,"summary":"No architecture changes; consistent gemspec conventions improve maintainability. ","findings":[]}

{"reviewer":"database","verdict":"PASS","severity":null,"summary":"No database impact.","findings":[]}

{"reviewer":"security","verdict":"PASS","severity":null,"summary":"No security impact; constraints formatting only.","findings":[]}

{"reviewer":"rails-security","verdict":"PASS","severity":null,"summary":"No Rails security impact.","findings":[]}

{"reviewer":"simplicity","verdict":"PASS","severity":null,"summary":"Simplifies gemspec constraints representation without changing semantics.","findings":[]}

{"reviewer":"rails-conventions","verdict":"PASS","severity":null,"summary":"Single-string required_ruby_version is the common RubyGems convention; notes doc is clear.","findings":[]}