Feature request: Surface portal/endpoint links for Azure resources in the dashboard

## Summary

When using Azure resource integrations like `AddFoundry()`, `AddAzureStorage()`, or `AddAzureKeyVault()`, the resource appears in the Aspire dashboard but shows **no clickable endpoints**. Local services display `localhost:XXXX` links, but Azure-backed resources show nothing — even though useful, navigable links exist for these resources.

## Current Behavior

Azure resources in the dashboard have no endpoints or links:
- No link to the Azure Portal page for the resource
- No link to service-specific portals (e.g., [ai.azure.com](https://ai.azure.com) for Foundry)
- No link to the resource's REST API endpoint

## Desired Behavior

Surface relevant links for Azure resources in the dashboard, such as:
- **Azure Portal link** — direct link to the resource in `portal.azure.com`
- **Service-specific portal** — e.g., `ai.azure.com` for Foundry, Storage Explorer URL for Storage
- **API/REST endpoint** — the actual endpoint URL the app connects to

## Concrete Example

`csharp
var foundry = builder.AddFoundry("foundry")
.AddDeployment("chat", FoundryModel.OpenAI.Gpt4oMini);
`

The Foundry resource knows its endpoint (e.g., `https://.services.ai.azure.com/models`) and its portal URL. Surfacing these in the dashboard would let developers:
- Quickly navigate to the Foundry portal to manage deployments, view metrics, or check quotas
- Copy the REST endpoint for testing with curl/Postman
- Verify which Azure resource the app is actually connected to

## Motivation

During inner-loop development with Aspire + Azure AI (Foundry), I frequently need to jump between the Aspire dashboard and the Azure/Foundry portals. Having these links directly in the dashboard would significantly improve the development experience — especially when debugging connection issues or verifying resource configuration.

This would benefit all Azure resource types, not just Foundry.

## Possible Implementation

Each `AddAzure*` hosting package could annotate the resource with URL metadata (e.g., via `WithUrls()` or a custom annotation) pointing to:
- The Azure Portal resource page (constructible from subscription/resource group/resource name)
- The service endpoint (already available in the connection string)
- The service-specific management portal (known per service type)