[13.2 Docs] Document Image Pull Policy and Docker Compose PullPolicy

[joperezr]

Summary

Aspire 13.2 introduces two related features around container image pull policies that have no reference documentation:

1. Image Pull Policy 'Never': A new option to set the image pull policy to Never, useful for scenarios requiring local-only images (e.g., locally-built images that shouldn't be pulled from a registry).

2. PullPolicy for Docker Compose: A new PullPolicy property added to the Docker Compose Service class, allowing users to control pull behavior in Docker Compose-based resources.

Current State

• Neither feature has dedicated documentation.
• The whats-new/aspire-13-2.mdx page mentions both briefly but there is no reference documentation explaining usage, available values, or code examples.
• No mention in integrations/compute/docker.mdx or app-host/docker-compose-to-apphost-reference.mdx.

What's Needed

1. Document the image pull policy API — explain the available pull policy values (Always, IfNotPresent, Never) and how to configure them on container resources. This could be added to the container/Docker hosting integration docs or as a section in the AppHost documentation.

2. Document PullPolicy in Docker Compose — add coverage of the PullPolicy property to the Docker Compose reference documentation (app-host/docker-compose-to-apphost-reference.mdx or integrations/compute/docker.mdx).

3. Include code examples showing common scenarios:

   • Using Never with locally-built images
   • Setting pull policy on Docker Compose services

Context

• Features introduced in Aspire 13.2
• Only covered in whats-new/aspire-13-2.mdx (section: Image pull policy, Docker Compose improvements)