[azure-ai-projects] Add sample and test authoring skills

[Glenn Harper (glharper)]

Summary

• add a package-local skill for authoring and updating sync/async samples after emitted or merged API changes
• add a package-local skill for authoring idiomatic pytest/Test Proxy coverage while keeping new recorded tests disabled
• include API-diff guidance, Python templates, package-specific conventions, and skill documentation

Validation

• verified skill frontmatter, directory names, and local Markdown links
• parsed all Python templates successfully
• checked the staged diff for whitespace errors

[azure-pipelines]

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