Add 'Ask @azure' context menu action to open GitHub Copilot Chat with AKS cluster context

## Bug / Feature Request

### Problem

Currently, there is no way to quickly ask GitHub Copilot Chat about a specific AKS cluster directly from the cluster context menu. Users who want to ask `@azure` about their cluster must manually open Copilot Chat and type out the cluster resource context themselves.

Additionally, the tree item ID for AKS clusters uses `name + resourceGroup` instead of the ARM resource ID, which can cause inconsistencies when identifying clusters programmatically.

### Expected Behavior

- A new **"Ask @azure"** context menu item should appear when right-clicking an AKS cluster in the Cloud Explorer (when GitHub Copilot Chat is activated).
- Clicking it should open GitHub Copilot Chat with a pre-populated query containing the cluster name and ARM resource ID, targeting the `@azure` participant.
- The cluster tree item ID should use the ARM resource ID for consistency.

### Proposed Solution

1. Add a new command `aks.askAzureCopilot` that:
- Resolves the selected AKS cluster node
- Opens Copilot Chat via `workbench.action.chat.open` with a pre-filled query: `@azure I'd like to talk about my Azure Kubernetes Service cluster (resource ID: ).`
2. Register the command in the context menu with visibility condition: `github.copilot-chat.activated`
3. Fix tree item ID to use `clusterResource.id` (ARM resource ID) instead of `name + resourceGroup`

### Files Affected

- `package.json` — command registration and menu contribution
- `package.nls.json` — localization string
- `src/extension.ts` — command registration
- `src/commands/aksAskAzureCopilot/aksAskAzureCopilot.ts` — new command implementation
- `src/tree/aksClusterTreeItem.ts` — tree item ID fix

### Additional Context

This integrates with the GitHub Copilot Chat `@azure` participant to provide a seamless "ask about my cluster" experience directly from the AKS extension tree view.

Start by reading src/extension.ts and the existing command and tree-item patterns, then inspect the five files listed in the issue. Verify the command registration, context-menu visibility, Copilot Chat query, and ARM resource ID behavior against the expected behavior; done means all requested files are updated and the action works only when Copilot Chat is activated.

Written by the indexing model from the issue text.