chore: add AGENTS.md and agent skills for making and reviewing icons - #2822

CodeQL Action major versions v1 and v2 have been deprecated. Please update all occurrences of the CodeQL Action in your workflow files to v3. For more information, see https://github.blog/changelog/2025-01-10-code-scanning-codeql-action-v2-is-now-deprecated/

Node.js 20 is deprecated. The following actions target Node.js 20 but are being forced to run on Node.js 24: actions/setup-python@v5, github/codeql-action/analyze@v2, github/codeql-action/init@v2. For more information see: https://github.blog/changelog/2025-09-19-deprecation-of-node-20-on-github-actions-runners/

The CODEQL_PYTHON environment variable is no longer supported. Please remove it from your workflow. This environment variable was originally used to specify a Python executable that included the dependencies of your Python code, however Python analysis no longer uses these dependencies. If you used CODEQL_PYTHON to force the version of Python to analyze as, please use CODEQL_EXTRACTOR_PYTHON_ANALYSIS_VERSION instead, such as 'CODEQL_EXTRACTOR_PYTHON_ANALYSIS_VERSION=2.7' or 'CODEQL_EXTRACTOR_PYTHON_ANALYSIS_VERSION=3.11'.

The setup-python-dependencies input is deprecated and no longer has any effect. We recommend removing any references from your workflows. See https://github.blog/changelog/2024-01-23-codeql-2-16-python-dependency-installation-disabled-new-queries-and-bug-fixes/ for more information.