Add signed macOS release pipeline

[vuon9]

Summary

• add signed/notarized macOS release workflow path
• document macOS release setup and signing notes
• adjust app/window/settings pieces needed for the release pipeline

Verification

• Khoa reported local npm run build passed before handoff
• Mini refreshed GitHub auth with workflow scope and pushed the branch

Notes

• Branch was handed off because the previous token lacked workflow scope for .github/workflows/* changes.
• Review should pay close attention to signing secrets, notarization variables, and release trigger behavior before merge.

[github-actions]

Package	Line Rate	Health
devtoolbox/internal/barcode	93%	✔
devtoolbox/internal/codeformatter	80%	➖
devtoolbox/internal/converter	65%	➖
devtoolbox/internal/datagenerator	81%	✔
devtoolbox/internal/datetimeconverter	75%	➖
devtoolbox/internal/jwt	47%	❌
devtoolbox/internal/numberconverter	0%	❌
devtoolbox/internal/settings	0%	❌
devtoolbox/internal/themes	0%	❌
Summary	68% (3613 / 5294)	➖

Minimum allowed line rate is 60%