Update issue triage workflow model and add agentics maintenance workflow

[TamasBoncz]

• Changed the model in the issue triage workflow from 'small' to 'gpt-5.4' for better performance.
• Introduced a new agentics maintenance workflow with various operations including closing expired issues, cleaning cache memories, and generating activity reports.
• Implemented scheduled and manual triggers for the maintenance workflow, allowing for flexible operation management.
• Added permissions and job definitions to handle different maintenance tasks effectively.

Fixes #141 #134 #129 #124

[github-actions]

⚠️ Deprecation Warning: The deny-licenses option is deprecated for possible removal in the next major release. For more information, see issue 997.

Dependency Review

✅ No vulnerabilities or license issues or OpenSSF Scorecard issues found.

OpenSSF Scorecard

Package	Version	Score	Details
actions/actions/checkout	df4cb1c069e1874edd31b4311f1884172cec0e10	🟢 5.9	Details Check Score Reason Code-Review 🟢 10 all changesets reviewed Binary-Artifacts 🟢 10 no binaries found in the repo Maintained ⚠️ 2 3 commit(s) and 0 issue activity found in the last 90 days -- score normalized to 2 Dangerous-Workflow 🟢 10 no dangerous workflow patterns detected CII-Best-Practices ⚠️ 0 no effort to earn an OpenSSF best practices badge detected Token-Permissions ⚠️ 0 detected GitHub workflow tokens with excessive permissions Fuzzing ⚠️ 0 project is not fuzzed Pinned-Dependencies 🟢 3 dependency not pinned by hash detected -- score normalized to 3 License 🟢 10 license file detected Packaging ⚠️ -1 packaging workflow not detected Signed-Releases ⚠️ -1 no releases found Security-Policy 🟢 9 security policy file detected SAST 🟢 8 SAST tool detected but not run on all commits Branch-Protection 🟢 5 branch protection is not maximal on development and all release branches
actions/github/gh-aw-actions/setup	c0338fef4749d08c21f8f975fb0e37efa17dda47	Unknown	Unknown

Scanned Files

• .github/workflows/issue-triage.lock.yml