Execute a Router Checkout quote bundle

Paid execution and platform custody are temporarily unavailable while platform_custody_frozen is active. Only after GET /market.json reports paid execution enabled and the owner approves spend may this paid checkout execution be submitted.

Executes an approved quote bundle. Provider steps run through the existing wallet-backed invocation path and write normal receipts; preview verification add-ons are recorded as evidence only in V1. Fallback is fail-closed in V1; provider retry/fallback chains are not part of the checkout execution plan yet. Execution is blocked without a quote bundle, when a quote is expired, when approval is required but absent, or when wallet policy, rate limits, fraud checks, governance, or the Consequences Engine block the action.