Add accessibility and keyboard-navigation tests for the extension

[ocularminds]

Context

The Docker Desktop extension has automated type, unit, and production-build checks, but no explicit accessibility gate for its decision, approval, and dossier views.

Scope

Cover semantic structure, keyboard use, focus behavior, and accessible labeling in the UI test suite.

Acceptance criteria

• Automated checks cover the decision feed, filters, approval panel, and dossier inspector.
• All interactive controls are reachable and operable with a keyboard.
• Focus is restored or moved predictably when dialogs and detail views open or close.
• Outcome and verification state are conveyed without relying on color alone.
• New critical or serious accessibility violations fail CI.