Meter-gated removal (7 consecutive zero-usage windows reached). Deletes:
- MCP tools: create_workstream, list_workstreams, update_workstream,
update_workstream_status
- MCP resource: state://workstreams/{topic_slug}
- Dead helpers: _LEGACY_MCP_* maps, _legacy_mcp_deprecation,
_meter_legacy_mcp, _attach_legacy_deprecation, _update_workplan_legacy_impl
TOOLS.md keeps a retired→preferred migration map (per backlog). Removed the
now-dead STATEHUB_MCP_LEGACY_METER guard in conftest. Retargeted the
create_workplan error-skip test to the preferred tool; dropped alias-only tests.
Staged on branch state-wp-0070-legacy-retirement — do not merge until the 7th
documented zero-usage window is captured.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>