[WIP] Fix check for rendering Mermaid diagrams

[Copilot]

Cloud agent has begun work on I'm still seeing it ... and will update this pull request as work progresses.

Original prompt

I'm still seeing it pinned as of today's build which seems to have your change

The tool call is renderMermaidDiagram and your check is includes('mermaid') ... if the tool names are not "toLower" somewhere else, I suspect this is your issue

The user has attached the following file paths as relevant context:

• .github/instructions/learnings.instructions.md
• .github/copilot-instructions.md
• AGENTS.md

Created from VS Code.

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