Add Agent Registry and CSGClaw agent type

[Rader]

Summary:

• Implemented the Agent Registry and CSGClaw agent type, enabling Code repositories to publish and manage CSGClaw Agent Templates via agent.toml through EE/SaaS Git callbacks.
• Added CSGClaw Sandbox lifecycle management, allowing explicit instance creation via API with custom environments/resources, and routing chat requests through the AIGateway proxy.
• Synchronized repository visibility with template publicity, introduced CSGClaw runtime profile initialization, and supported public sharing of agent instances.

[Rader]

Depends on #1359

[HaiHui886]

lgtm