Add strict Conductor orchestration mode to Poteto Mode

[RomiSinghio]

Implement the approved Savari Conductor-mode design: fixed invoking coordinator, isolated Claude/Codex/Cursor workers, strict receipts, durable budgets, and no fallback. This work stacks on PR #50 and avoids provider-dispatch.md while PRs #48 and #31 remain open.

[RomiSinghio]

Superseded by the Savari-owned implementation in TMS-1778.