Expose calling project context to AI agents

[ocots]

Summary

• Add the calling repository to the runtime context sent to the agent.
• Keep the context generic so the same workflow can serve CTBase and other repositories.
• Preserve the provider, model, prompt, and secret-safety behavior.

The agent can now distinguish the project that invoked the workflow without hard-coding a repository name in the agent instructions.

Related PRs

• Generic project-summary instructions: Add playful role-play to the hello agent Handbook#21
• Generic project prompt in CTBase: Use a generic project summary prompt CTBase.jl#561

Test plan

• Validate the workflow as YAML.
• Run git diff --check.
• Run the CTBase workflow after merging the related PRs.