🧩 Add AGENTS.md file to align with AGENTS.md standards

📄 Description

This repository currently includes a .github/copilot-instructions.md file, but it does not yet have an AGENTS.md file to describe how AI agents (e.g., Copilot, MCP, or LLM-based assistants) should interact with this repository.

To align with emerging AGENTS.md standards and ensure consistent developer experiences across Azure SDK repositories, we should add a top-level AGENTS.md file that defines:

• Repository purpose and scope
• Key workflows, commands, and automation boundaries for agents
• Supported contribution actions (e.g., PR triage, labeling, issue summarization)
• Guidance for safe and effective agent interactions with CI/CD pipelines, SDK tests, and documentation

✅ Proposed Tasks

• Review existing .github/copilot-instructions.md and identify relevant guidance to merge or reference in AGENTS.md.
• Create an AGENTS.md file at the root of the repository following the canonical structure defined at AGENTS.md.
• Cross-link between .github/copilot-instructions.md and AGENTS.md for discoverability.
• (Optional) Add repository metadata in AGENTS.md to describe SDK-specific automation workflows (e.g., codegen, API review, test matrix).

📘 Example References

• AGENTS.md — canonical spec
• Example .github/copilot-instructions.md

🧭 Context

This issue is part of a broader initiative to introduce AGENTS.md across all Azure SDK repositories (see the Azure SDK org overview) to standardize AI agent documentation and improve consistency in automation and Copilot-based contributions.