Add topology-scoped Space prompts

[Yuqing (mydmdm)]

Summary

• derive Prompt Frame scope from direct Agent Node connections
• keep unconnected Prompt Frames Space-global and freeze scope at first explicit interaction
• display the derived scope in the Prompt badge and document the lifecycle contract

Behavior

A Prompt Frame with no direct Agent neighbours applies to every Agent in the Space. Once it has direct Agent connections, it applies only to those Agents. Edge direction and style are ignored, non-Agent connections do not change global scope, and traversal remains direct-only.

Create-only and edge edits do not realize an Agent. The first message or external ACP control reads one current topology snapshot and persists the compiled Prompt in the immutable WorkloadSpec. Create-and-start realizes only after Agent creation completes.

Validation

• pnpm typecheck
• pnpm format
• pnpm lint:fix
• focused shared, server, RFS lifecycle, and Web badge tests
• full shared and Web test suites

Fixes #166