Contract 1.7.1

Scoped battle intelligence now uses the participant-time index for player, clan and collection windows instead of filtering time only after joining back to battles. battles_meta_cards also derives its denominator from the same card expansion rather than scanning the scoped observations a second time. This fixes an observed burst where four concurrent clan/collection card-meta calls exhausted the MCP Lambda's 25-second limit. Response meta now includes events_pending: 0 and feedback_responses_pending: 0 when each queue is empty, restoring the EVERY-response promise made in 1.0.0 and letting scheduled consumers skip empty ledger reads.