🧹 Refactor VS Code AGENTS.md generation to reduce duplication

[64andrewwalker]

🎯 What: Reduced code duplication in src/infrastructure/adapters/vscode.rs by extracting a common pattern for generating AGENTS.md sections into a helper function.
💡 Why: The original code had three nearly identical blocks for Policies, Actions, and Agents. This refactoring makes the code cleaner, reduces duplication, and centralizes the formatting logic.
✅ Verification:

• Manually verified the refactored code against the original logic.
• cargo fmt --check passed.
• Received a positive code review confirming correctness and adherence to Rust idioms.
  ✨ Result: Improved maintainability and readability of the VS Code adapter.

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PR created automatically by Jules for task 5935896873885960423 started by @64andrewwalker

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