[AzureDevOpsExtension] Add a one-click “Fix” flow to start sessions from Azure DevOps work item descriptions

### Summary

I can open Azure DevOps work items in the canvas, but I cannot easily pass the work item’s **title and description** into a Copilot session to start implementation.

I would like a workflow similar to the existing **Fix** button for pull request comments: one click should load the work item context into the active session

### Environment

App version 1.1.14
Windows 10.0.26200 Build 26200
azure-devops-copilot-plugin 0.1.53

### Problem

When I open a work item in the Azure DevOps canvas, I can view its details, but I still have to manually copy/paste the title and description into chat before starting work.

### Expected behavior

A work item should expose an action like:

- **Fix**

- or **Implement**

That action should send the work item’s title/description to the active session

### Current behavior

- Work items can be opened in the Azure DevOps canvas.

- The work item context is visible there.

- The context is not transferred into the session automatically.

### Why this matters

This would make the Azure DevOps integration much more useful for starting work directly from the issue/task, without manual context copying.

### Repro steps

1. Open Azure DevOps canvas.

2. Open a work item.

3. Observe the title and description are visible.

4. Try to start implementation from that item.

5. The session does not receive the work item context automatically.

### Notes

This should mirror the existing **Fix** experience available for pull request comments, but for Azure DevOps work items.

Commencez par comparer le flux Fix existant pour les commentaires de pull request avec la vue canvas des work items Azure DevOps décrite ici. Vérifiez qu’une action Fix ou Implement en un clic transfère le titre et la description du work item dans la session active et que le flux fonctionne depuis un work item ouvert.

Rédigé par le modèle d'indexation à partir du texte de l'issue.