agents

Add error messages skill documentation outlining best practices for user-facing error messages. Includes five essential rules, four anti-patterns to avoid, and structured message examples to enhance clarity and user experience.

Update Azure DevOps skill documentation to clarify usage of `az boards work-item` commands. Added important notes regarding the exclusion of `--project` for `show` and `update` commands, and introduced new examples for fetching work items from URLs. Updated best practices to reflect these changes.

Enhance Azure DevOps skill documentation with detailed pull request creation steps, emphasizing the extraction of organization, project, and repository from the git remote URL. Added critical warnings against using `az devops configure` and included required flags for PR management commands.