Advisory: Az.Accounts 5.5.1 + PnP.PowerShell crash the PS 7.4 worker with MissingMethodException (AddHttpClient/AddOptions)

## Summary

When a PowerShell 7.4 Functions app loads **both** `Az.Accounts` 5.5.1 and `PnP.PowerShell`, any PnP cmdlet that builds an HTTP client (e.g. `Connect-PnPOnline`) throws a `System.MissingMethodException` inside `PnP.Framework`. Downgrading to **`Az.Accounts` 5.5.0** resolves it.

This has been reported by multiple customers. Filing as an advisory so others hitting the same exception can find the cause and workaround, and to flag a possible assembly-isolation issue in the worker.

## Exact exception

```
System.MissingMethodException: Method not found:
'Microsoft.Extensions.DependencyInjection.IServiceCollection
Microsoft.Extensions.DependencyInjection.OptionsServiceCollectionExtensions.AddOptions(
Microsoft.Extensions.DependencyInjection.IServiceCollection)'.
at Microsoft.Extensions.DependencyInjection.HttpClientFactoryServiceCollectionExtensions.AddHttpClient(IServiceCollection services)
at Microsoft.Extensions.DependencyInjection.HttpClientFactoryServiceCollectionExtensions.AddHttpClient(IServiceCollection services, String name, Action`1 configureClient)
at PnP.Framework.Http.PnPHttpClient.AddHttpClients(IServiceCollection collection, String UserAgent)
at PnP.Framework.Http.PnPHttpClient.BuildServiceFactory()
at PnP.Framework.Http.PnPHttpClient..ctor()
...
at PnP.PowerShell.Commands.Base.ConnectOnline.ProcessRecord()
```

## Root cause

The two modules ship conflicting `Microsoft.Extensions.*` assemblies that get co-loaded into the worker process:

| Assembly | Source | Version |
|---|---|---|
| `Microsoft.Extensions.Http` | PnP.Framework (bundled with PnP.PowerShell 3.2.0) | **8.0.0.0** |
| `Microsoft.Extensions.Options` | Az.Accounts **5.5.1** | **10.0.0.0** |

`Microsoft.Extensions.Http` 8.0.0.0 was compiled against the `AddOptions(IServiceCollection)` overload, which is not present in the `Microsoft.Extensions.Options` 10.0.0.0 that resolves in the worker → `MissingMethodException`.

Confirmed by changing only the `Az.Accounts` version (everything else identical):

| `Az.Accounts` | `Microsoft.Extensions.Options` loaded | Result |
|---|---|---|
| 5.5.1 | 10.0.0.0 | ❌ `MissingMethodException` |
| 5.5.0 | 8.0.0.0 | ✅ works |

## Reproduction

`requirements.psd1`:

```powershell
@{
'Az.Accounts' = '5.5.1'
'Az.Resources' = '10.0.0'
'Az.Storage' = '9.7.0'
'PnP.PowerShell' = '3.2.0'
'Az.KeyVault' = '6.5.0'
}
```

In an HTTP-triggered function:

```powershell
Import-Module Az.Accounts
Import-Module PnP.PowerShell
Connect-PnPOnline -Url 'https://contoso.sharepoint.com' -ClientId '' -ClientSecret ''
# -> System.MissingMethodException in PnP.Framework.Http.PnPHttpClient.AddHttpClients
```

Both modules are required to reproduce — `Az.Accounts` alone does not load `Microsoft.Extensions.Http`; `PnP.Framework` supplies the `Http` 8.0.0.0 assembly and is the caller of `AddHttpClient`.

## Workaround

Pin `Az.Accounts` to **5.5.0** in `requirements.psd1`:

```powershell
'Az.Accounts' = '5.5.0'
```

## Environment

- Functions runtime: 4.1048.200.26180 (Core Tools 4.12.1)
- Worker: PowerShell 7.4.13 (.NET 8)
- `FUNCTIONS_WORKER_RUNTIME_VERSION`: 7.4
- Managed dependencies enabled

Start with the requirements.psd1 reproduction and the HTTP-trigger entry point that imports Az.Accounts and PnP.PowerShell, then run Connect-PnPOnline with the listed versions. The issue names no worker file or test and does not define a concrete change; done would require a confirmed worker-side resolution or an explicit decision to document the incompatibility and workaround.

Written by the indexing model from the issue text.