Release AIKernel.Providers v0.1.2 provider driver boundary (#2)

## Summary
This PR releases AIKernel.Providers v0.1.2 as the provider substrate and driver boundary.

## Changes
- Aligns provider packages with official AIKernel.NET, Core, and Control v0.1.2 packages.
- Stabilizes provider substrate, manifest, router, council, audio, compute, perception, standard providers, and Microsoft AI provider surfaces.
- Preserves dependency boundaries: providers translate external specificity into AIKernel capability contracts.
- Keeps native/runtime-specific implementations outside the generic provider substrate.

## Validation
- dotnet restore
- dotnet build
- dotnet test

## Release
This PR prepares AIKernel.Providers v0.1.2 package publication and GitHub release.

Release 0.1.1: Converge provider capabilities (#1)

## Summary
- Finalizes the AIKernel.Providers 0.1.1 provider surface.
- Aligns provider categories across source, tests, solution folders, documentation, and Python native loading.
- Moves ChatOpenAIProvider into the Chat category to match its provider role.
- Keeps LLM, Compute, Pipeline, Standard, and Chat providers consistently organized.

## Validation
- Release build passed with package generation disabled.
- .NET provider tests passed.
- Python wrapper tests passed.