chore: add agentic first-time contributor workflow

[Junnygram]

Description

This PR replaces the legacy (or missing) newcomer welcoming logic with a modern, agentic workflow using the gh-aw framework. This is part of the effort to standardize and harden newcomer onboarding across the Meshery ecosystem.

Key Features:

• Personalized Onboarding: The assistant analyzes the PR content and provides tailored resource links based on the specific files touched (e.g., schemas vs. documentation).
• Hardened Bot Filter: Includes a production-grade filter to ignore Dependabot, Copilot, and other automated agents, reducing notification noise.
• DCO Compliance: Automatically checks for commit sign-offs and provides immediate fix instructions if they are missing.
• Security: Hardened with checkout: false to prevent untrusted code execution during the pull_request_target event.

Next Steps

This workflow is being evaluated for its effectiveness in providing high-quality, relevant guidance to first-time contributors.

[gemini-code-assist]

Code Review

This pull request introduces a GitHub Actions lock file and updates the .gitattributes file to manage these locks. Several issues were identified: the version specified for actions/github-script appears to be invalid, the repository format for the setup action is incorrect, and the .gitattributes pattern does not correctly target the new lock file path.

[gemini-code-assist]

The version v9.0.0 for actions/github-script appears to be incorrect, as the current major version is v7. Using a non-existent version string may cause the workflow to fail during action resolution.

[gemini-code-assist]

The pattern .github/workflows/*.lock.yml does not match the path or file extension of the lock file added in this PR (.github/aw/actions-lock.json). This prevents the linguist-generated and merge=ours attributes from being applied to the intended file.

.github/aw/*.json linguist-generated=true merge=ours

[gemini-code-assist]

The repo field github/gh-aw-actions/setup uses an invalid format. GitHub repository references should follow the owner/repo pattern. If the action is located in a subdirectory, the repo field should typically point to the repository root.