Expand Uno.UITests for the workbench and operator flows

[KSemenenko]

Problem

The future workbench surface is much larger than the current UI suite, so the repo needs tracked UI-test growth for operator scenarios.

Scope

• Track UI automation for the workbench shell, Toolchain Center, session composer, approvals, file surfaces, and Git flows
• Keep tests aligned with the desktop-first UI direction
• Preserve the existing real UI-test philosophy

Out of scope

• Replacing UI tests with mock-heavy checks
• Non-UI runtime tests

Implementation notes

• Use Uno.UITests to validate real operator flows
• Keep the issue aligned with the current shell and future workbench growth
• Ensure approvals and review flows become first-class regression coverage

Definition of Done

• The issue defines the UI flows that must gain automation coverage as the product grows
• Later feature work can add UI tests without re-deciding the target coverage set

Verification

• Review the issue against the feature spec and current UI-test policy

Dependencies

• Parent epic: [Epic] Expand automated validation for the control-plane product #21