Single-payload recovery

Both manual ("Issue notice") and scheduled ("Sweep") triggers below build the same canonical payload — one row per overdue loan — and POST each to one thin n8n webhook (SMTP + sheet append only). No merge step, no shared agent invocation, no chance of an empty input. This replaces the previous design where a 7-day schedule + manual webhook merged into a single agent call and produced inconsistent emails when only one input fired.