Backend solution (c) shipped in nick/backend@bdbcc32 — endpoint now reuses
existing pending Payments instead of colliding on the unique index.
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
Captures the E11000 collision on the uniq_pending_request_network_by_buyer_session
index, identifies reused purchaseRequestId as the root cause, and lays out the
mongo unblock, frontend id-rotation, and backend idempotency fixes.
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>