One-time $10 OpenClaw signup bonus. Idempotent: replays return the existing balance without double-crediting.

Amount is server-controlled (SIGNUP_BONUS_CENTS); the caller has no input beyond their authenticated identity. Replaces the legacy pattern of having the frontend call /api/wallet/credit directly (AUTH-002).

Seats accounts (every account since 2026-07-31) get a 200 no-op: hosting credit buys nothing on seats, so minting it is pure ledger noise — but the response MUST stay 200 because the openclaw deploy flow (frontend /api/openclaw/deploy) treats any non-ok here as fatal and aborts the whole signup.