B-Fi Check — staging

Plane 3 live on InterServer.

• /healthz — Odoo JSON-RPC + BLAKE3 ledger chain
• /v1/ledger/verify
• /v1/ledger/tail

POST /v1/journal — capability-gated, balanced-only (the only write path).
POST /v1/proposals — Assist proposals, never applied.
POST /v1/ledger/mutate — 405 by design.