implement-plan

Use to implement a structured implementation plan (e.g. temp/impl_plans/issue-*.md) phase by phase. Trigger when the user asks to implement, execute, realize, or "do" an implementation-plan file. Orchestrates a phase-developer subagent and a plan-correspondence-verifier subagent for each phase, commits each verified phase, then walks the Final Checklist. Invoke explicitly — it makes commits and spawns many subagents.