Per-agent message restrictions, gated code install, and onboarding wayfinding

What this changes for operators

• Operators deploying public-facing or sandboxed agents should evaluate tools.message.crossContext and tools.message.actions.allow overrides to restrict agent message sends to the current conversation without changing the global bot policy.
• Operators running long-horizon OpenClaw sessions should know that session memory is now bounded: the memory dreaming promotion cap compacts oldest auto-promoted sections while preserving user-authored notes. Unbounded auto-memory growth is no longer the default behavior.
• Operators deploying OpenClaw for new users should test the improved CLI onboarding wayfinding: setup, onboarding, configure, and channel commands now explain the next useful command at each step.