[Feature]: Create mirror for when PowerShell Gallery is down

### Description of the new feature

PowerShell Gallery is not reliable, and currently it experiences problems due to the `*.azureedge.net` CDN retirement.

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I have a meta issue / feature request that tracks more issues I've encountered.

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AWS hosts a mirror of their modules, which is great for when PowerShell Gallery is down.

* Announcement:
* Links to latest:
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Maybe you could do the same?

### Proposed implementation details (optional)

Add release artifacts as ZIP to GitHub releases?

* Az currently releases MSI installers, which is helpful for Windows users. Linux and Mac?

Publish modules to MCR too? Seems you've started testing with that already.

* GUI:
* API:

The issue names no repository files or tests; start by reviewing the linked PowerShell Gallery discussions and the existing MSI, GitHub release, and MCR publishing paths mentioned here. Define the supported modules, platforms, artifact format, and fallback behavior before implementation; done means an agreed, reliable mirror is available when PowerShell Gallery is unavailable.

Written by the indexing model from the issue text.