Cut Practice model to role-neutral WorkRunStore and five RoleProfiles

[shenjiecode]

Scope

Delete the old "one Agent switches professions via Practices" model and replace it with role-neutral run state plus five single-identity RoleProfiles.

Clean cut

• Delete the practices registry, practiceIds, methodology-as-primary-model, and old schema entries.
• Retire Reviewer v2 / local-Git active path from the new runtime (assets preserved in Git history; only independently reusable generic modules may be re-extracted later under a separate issue).
• Write a small, role-neutral WorkRunStore with Task/role/skill binding; do not mechanically rename PracticeRun.
• Convert runtime assembly to profile/registry-driven (no if reviewer else kernel).

RoleProfiles

• Build leader, designer, implementor, assessor, operator profiles with minimal SOULs and tool surfaces.
• Implement a closed, digest-validated Skill loader; keep noSkills:true so environment auto-discovery stays disabled.
• Keep existing generic Worker tests green.

Exit gate

All Worker tests green; five profiles assemble; old Practice runtime no longer selectable.

References

• AGENTS.md, docs/rules/implementation.md, worker/agent/config/role-profile.mjs, worker/role-profiles/