System.Drawing.Common package omits required System.Formats.Nrbf dependency

### Description

`System.Drawing.Common` version `11.0.0-preview.7.26381.103` ships `lib/net11.0/System.Private.Windows.Core.dll`, which has a direct assembly reference to `System.Formats.Nrbf, Version=11.0.0.0`. However, the package's `net11.0` nuspec dependency group declares only `Microsoft.Win32.SystemEvents`.

As a result, NuGet restore does not resolve `System.Formats.Nrbf`, and publish does not copy `System.Formats.Nrbf.dll` or include it in the ReadyToRun compiler reference closure. This produces an invalid deployment closure.

### Reproduction

1. Restore or publish an application that references `System.Drawing.Common` `11.0.0-preview.7.26381.103` for `net11.0`.
2. Inspect `project.assets.json`: the `System.Drawing.Common` target entry lists these runtime assets:
- `System.Drawing.Common.dll`
- `System.Private.Windows.Core.dll`
- `System.Private.Windows.GdiPlus.dll`
3. The same entry contains only this dependency:
- `Microsoft.Win32.SystemEvents`
4. `System.Formats.Nrbf` has no resolved node and is not copied to publish output.
5. ReadyToRun/Crossgen2 fails while processing `System.Private.Windows.Core.dll`:

```
Error: Failed to load assembly 'System.Formats.Nrbf'
Internal.TypeSystem.TypeSystemException+FileNotFoundException: Failed to load assembly 'System.Formats.Nrbf'
```

Adding the matching `System.Formats.Nrbf.dll` to the Crossgen2 reference set makes the same compilation complete successfully.

### Source cause

`System.Private.Windows.Core.csproj` references `System.Formats.Nrbf`. `System.Drawing.Common.csproj` packs `System.Private.Windows.Core` using a project reference with `Pack=true` and `PrivateAssets=all`, which embeds the assembly but suppresses its NuGet dependency edge from the resulting `System.Drawing.Common` package.

### Expected behavior

The `net11.0` `System.Drawing.Common` package dependency group should make `System.Formats.Nrbf` available to consumers, so publish and ReadyToRun receive a complete runtime assembly closure.

### Suggested fix

Add a `System.Formats.Nrbf` package dependency to `System.Drawing.Common` for the applicable target frameworks, or otherwise change the package authoring so the dependency of the packed `System.Private.Windows.Core` asset is propagated.

### Additional context

This was observed while investigating https://github.com/dotnet/runtime/issues/132225. The same missing manifest edge appears in `11.0.0-preview.6.26359.118`; .NET 11 preview 7 Crossgen2 exposes it during ReadyToRun compilation.

Start by comparing System.Private.Windows.Core.csproj and System.Drawing.Common.csproj to see how the packed project reference affects dependencies. Restore or publish the net11.0 reproduction and inspect project.assets.json, then run the ReadyToRun/Crossgen2 scenario. Done means the package exposes System.Formats.Nrbf and publish includes it in the runtime and compiler reference closure.

Written by the indexing model from the issue text.