feat(core): migrate workspace + runtimes to TanStack Query (Phase 3+4)
- Create core/workspace/ with queries (members, agents, skills, list) and mutations
- Create core/runtimes/ with queries
- Migrate 11 consumer files from useWorkspaceStore.members/agents/skills to useQuery
- Replace all WS refreshMap entries with qc.invalidateQueries
- Simplify workspace store: delete members/agents/skills fields + refresh methods,
hydrateWorkspace becomes synchronous (TQ auto-fetches on component mount)
- Delete useRuntimeStore (no consumers left), runtimes-page uses local useState + TQ
- Remove workspace→runtime cross-store dependency
- Clean up dead test helper mocks
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>