Consolidate Reploid journeys and remove dead code

[clocksmith]

Summary

• establish canonical, machine-verified critical user journeys for Poolday, Zero, and X
• integrate journey verification with release and surface-claim gates
• archive completed planning material and remove superseded TODO/status documents
• remove unreachable legacy UI, arena, scheduler, registry, negotiation, style, and test code
• share Poolday policy validation between browser and server routing
• harden registry validation and update generated manifests/configuration

Validation

• npm run test:unit — 1492 passed, 18 skipped
• npm run test:integration — 342 passed, 9 skipped
• npm run verify:journeys
• npm run verify:surface-claims
• node scripts/validate-registry.js
• npm run verify:module-system
• git diff --check

Browser tests were intentionally not run.