Mission Control Phase 1: add production-sized fixture seeding path for AC5 perf assertions

[krusty-agent]

Summary

• add API-backed seeding helper for AC5 perf harness (/api/lists/create + /api/items/add)
• wire AC5a/AC5b to prefer seeded production-sized fixture data when MISSION_CONTROL_FIXTURE_PATH enables seeding
• keep UI setup as fallback when token/Convex URL are unavailable
• annotate perf metrics with seeded/fallback mode context

Validation

• npm run test:e2e -- e2e/mission-control-phase1.spec.ts -g "AC5"
  • result: 2 skipped in local env (expected due auth shell/environment gating), no runtime/spec errors

Notes

• Commit: ebf0231

[krusty-agent]

Superseded by consolidated integration PR #161: #161