STATE-WP-0069: MCP Phase 1 deprecation + open_workplans summary alias

Complete MCP legacy deprecation coverage (resource + docstrings + TOOLS.md).
Dual-write open_workplans on /state/summary alongside open_workstreams;
get_domain_summary prefers the new key. T06 internal rename started.

api/schemas/state.py

@@ -81,6 +81,7 @@ class StateSummary(BaseModel):
     blocked_tasks: list[TaskRead] = []
     recent_progress: list[ProgressEventRead]
     open_workstreams: list[WorkstreamWithDeps]
+    open_workplans: list[WorkstreamWithDeps] = []
     next_steps: list[NextStep] = []
     domains: list[DomainSummary] = []
     contribution_counts: dict[str, int] = {}