Add Agent Framework examples

[jsturtevant]

Adds local and remote Microsoft Agent Framework examples for Hyperlight Unikraft.

Summary:

• Add offline local inference example using llama-cpp-python.
• Add remote GitHub Models example.
• Add pyhl env forwarding and a Python dev base stage for building native deps.

[Copilot]

Pull request overview

This PR adds two end-to-end Microsoft Agent Framework examples (one fully offline, one using GitHub Models remotely) and extends the pyhl runner to support forwarding environment variables into the guest Python process. It also refactors the Python runtime Dockerfile to expose a reusable “python-dev” stage for building native dependencies against the same ABI as the shipped Python base image.

Changes:

• Add pyhl run --env NAME[=VALUE] support to inject/forward environment variables into the guest Python process, with unit tests.
• Add a remote Agent Framework example that calls GitHub Models from inside the micro-VM (network restricted via --net-allow), with a minimal initrd builder.
• Add a local/offline Agent Framework example using llama-cpp-python + a baked-in GGUF model, including a matching Python dev base build flow for native deps.

Reviewed changes

Copilot reviewed 12 out of 12 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
runtimes/python.Dockerfile	Introduces a python-dev stage and ensures shared-library cache is refreshed after Python install for dev-image usability.
host/src/bin/pyhl.rs	Adds --env parsing + injection prelude for guest Python, plus unit tests.
examples/agent-framework-remote/README.md	Documents the remote GitHub Models Agent Framework example and its pyhl/networking flow.
examples/agent-framework-remote/Justfile	Adds build/rootfs/setup/run automation for the remote example using the driver/pyhl stack.
examples/agent-framework-remote/Dockerfile	Builds a minimal initrd: shipped hl_pydriver + agent-framework-core + cert/DNS config, packed as CPIO.
examples/agent-framework-remote/agent.py	Implements a synchronous BaseChatClient that POSTs to GitHub Models (OpenAI-compatible) from inside the guest.
examples/agent-framework-remote/.gitignore	Ignores generated kernels/initrds and local pyhl state for the remote example.
examples/agent-framework-local/README.md	Documents fully offline inference with llama-cpp-python and the rationale for build/runtime constraints.
examples/agent-framework-local/Justfile	Adds build/rootfs/run automation for the local offline example, including local Python base image build targets.
examples/agent-framework-local/Dockerfile	Builds an initrd containing agent-framework-core, llama-cpp-python (built SSE-only), and a downloaded GGUF model.
examples/agent-framework-local/agent.py	Implements a local llama.cpp-backed BaseChatClient plus stdlib stubs needed for the trimmed Python base.
examples/agent-framework-local/.gitignore	Ignores generated kernels/initrds for the local example.

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