Add pi-acp to the ACP catalog.

⛰️ Features

• (agents) Add pi-acp to the ACP catalog (#685)
• (providers) Add SuperGrok BYO subscription (#676)
• Ship Claude Code and Codex agent plugins (#683)
• Add AWS Bedrock, Azure, Vertex built-in providers (#647)

🐛 Bug Fixes

• (sdk) Preserve token limits and upstream errors (#692)