Add monitoring/reporting for wallet transaction mismatches between PostgreSQL and ClickHouse

Overview

Create weekly monitoring and reporting to identify subscriptions where sum(postgres consumption) does not match sum(clickhouse consumed). This will provide visibility into wallet transaction discrepancies and help us stay on top of these issues proactively.

Requirements

Phase 1: Weekly Mismatch Report

Generate weekly reports for all overaged subscriptions that identify:

Overaged subscriptions with mismatches in sums (beyond rounding errors)
Mismatch delta per subscription
Unique transaction IDs with mismatches, along with delta per transaction ID
If no mismatches found for the week, report that as well

Phase 2: Notification & Monitoring Integration

Integrate with existing usage billing job monitoring for notifications
Assign weekly monitoring responsibility to the on-call team member
Reuse existing monitoring infrastructure where possible

Phase 3: Remediation Steps

Identify and document remediation steps for when mismatches are found
Create action items based on debugging findings

Context

Currently, wallet_transactions are not easily accessible in ClickHouse
Comparative analysis requires querying two separate sources (PostgreSQL and ClickHouse)
Access to production console is limited, making manual validation difficult
Starting with overaged subscriptions; can expand to all subscriptions later if needed

Future Considerations

Eventually migrate PostgreSQL wallet transactions and consumer/subscription_wallet tables to ClickHouse (potentially via Siphon)
This would enable seamless dashboard/query monitoring within ClickHouse
Would eliminate the need for cross-source analysis

Closes #15772 - Investigation: Credit Mismatch Between ClickHouse and PostgreSQL Wallet Transactions