Remove non-functional weekly maintenance workflow

[Copilot]

The automated weekly maintenance workflow attempted to create issues and assign them to the project-maintainer agent using GitHub GraphQL mutations that are not currently supported.

Changes

• Removed .github/workflows/weekly-maintenance.yml - 161 line workflow file that created maintenance issues on a cron schedule
• Updated AGENTS.md - Removed "Weekly maintenance tasks" from Project Maintainer responsibilities
• Updated .github/agents/project-maintainer.md - Removed "Weekly Maintenance Tasks" section and adjusted description from "weekly" to "regularly" for monitoring cadence

The Project Maintainer agent retains all core functionality (dependency management, issue triage, project health monitoring, enhancement planning) without the broken automation.

Original prompt

---

This section details on the original issue you should resolve

<issue_title>[Feature]: Remove weekly maintenance</issue_title>
<issue_description>### Problem Statement

The automatic weekly maintenance task does not work and should be removed

Proposed Solution

Just remove the workflow until GitHub adds built-in support for this.

Alternatives Considered

No response

Usage Examples

Benefits

The existing attempt does not work and is confusing.

Priority

Medium - Would improve my workflow

Willingness to Contribute

Yes, I can submit a pull request

Additional Context

No response

Checklist

• I have searched existing issues to ensure this is not a duplicate
• I have provided a clear description of the feature
• I have explained why this feature would be useful</issue_description>

Comments on the Issue (you are @copilot in this section)

• Fixes [Feature]: Remove weekly maintenance #51

---

💬 We'd love your input! Share your thoughts on Copilot coding agent in our 2 minute survey.