[agent-issue]: Allow agent-supplied priority on work items #2354

Problem summary

Allow an agent to supply the priority of an Azure DevOps work item through ado-aw safe outputs, rather than requiring a fixed workflow-level value or manual triage after the run.

An agent investigating failures or triaging findings can determine that different work items have different urgency. It should be able to express that decision in Microsoft.VSTS.Common.Priority.

Current behavior / reproduction details

Source inspection of the default branch shows:

• CreateWorkItemParams exposes title, description, and tags, but no agent-supplied priority; unknown fields are rejected.
• UpdateWorkItemParams likewise does not expose priority.
• Creation supports operator-configured custom-fields, but a static value does not let the agent choose priority per work item.

Configure work-item safe outputs and ask an agent to create or update work items with priorities based on its findings: the agent-facing schemas have no supported priority parameter. This is a feature request based on schema inspection, not a reported live execution failure.

Expected behavior

Support an optional agent-supplied priority for work-item creation and updates, mapped to Microsoft.VSTS.Common.Priority, while preserving the safe-output permission model.

Proposed next step

• Add priority to the agent-facing parameters and carry it through persisted proposals and execution.
• Validate supported values and provide clear errors for invalid or disallowed values.
• Keep operator control consistent with existing safe-output configuration, and document precedence if a configured custom field also sets priority.
• Preserve existing behavior when priority is omitted: creation keeps its configured/default behavior, and updates leave existing priority unchanged.
• Cover creation, priority-only updates, omitted/invalid values, and configuration enforcement with tests; document usage.

Authoring context

Prepared after reading .github/agents/ado-aw.agent.md and inspecting the work-item safe-output implementations. Filed directly in githubnext/ado-aw at the user's request.