Harden PayGate operations and recovery

[Phloraxx]

Summary

Hardens PayGate from a working SMS verifier into an operationally recoverable payment service while preserving fail-closed matching.

Payment correctness

• classifies paid/late using the bank/provider occurrence timestamp, not delayed SMS arrival time
• preserves exact payable amount, unique RRN and stale-evidence invariants for automatic and manual matching
• exposes fingerprint-pool capacity and alerts at 70%/95%

Exception handling and audit

• persistent review cases for parse errors, missing RRN, unmatched, ambiguous and contradictory evidence
• audited operator resolution/manual matching
• immutable evidence plus actor/entity/action audit events

Reconciliation and refunds

• CSV/TSV/XLSX bank-statement imports with debit filtering, duplicate hashes/RRNs, conflict reports and XLSX archive limits
• report-only reconciliation; no automatic status mutation
• bounded/idempotent manual refund lifecycle with bank references and signed webhook events

Reliability and recovery

• connector/capacity/webhook/reconciliation/backup alerts
• optional signed durable operator-alert webhook with retries and dedupe
• configurable evidence redaction/retention
• scheduled local or S3-compatible backups
• archive verification and temporary SQLite restore drills
• idempotent managed rate-limit configuration across restarts

Operator UI and documentation

• review, reconciliation, alert, refund and audit pages
• dashboard capacity/review/alert/backup telemetry
• backup create/verify/restore controls
• complete operational runbook and updated acceptance plan

Verification completed

• npm audit --audit-level=high (0 vulnerabilities)
• frontend typecheck and production build
• Go formatting, all tests, vet and diff checks
• full go test -race -count=1 ./...
• migration up -> down 1 -> up on a clean SQLite database
• production Docker image build
• fresh-volume HTTP/CLI acceptance covering payment, SMS, public redaction, duplicates, reviews, refunds, backups, restore drill and container recreation/persistence