Add playful role-play to the hello agent

[ocots]

Summary

• Turn the generic hello agent into a playful round-table introduction.
• Ask it to invent a fictional provider-inspired name.
• Present it as a coding and software-engineering specialist working with the Control Toolbox organization.
• Keep the provider, model, workflow, and secret-safety instructions explicit.

The fictional identity is explicitly framed as role-play so the agent does not present it as a real identity.

Related work

• Generic AI workflow: Expose provider and model to AI agents CTActions#74
• CTBase caller: Use merged AI agent workflow and Handbook CTBase.jl#560

Test plan

• Review the revised agent instructions.
• Run git diff --check.
• Run the CTBase workflow after merging this PR.

[ocots]

The agent instructions now also require a short, generic overview of the calling project. The project is identified through runtime context, so the instructions do not mention CTBase or any other repository by name.

The corresponding workflow changes are proposed in CTActions PR #75 and CTBase PR #561.