feat: complete data mirror — all customers + 115K invoices
- 8,636 terminated customers imported (disabled=1, terminate reason/company/notes preserved)
- Total customers: 15,303 (100% of legacy)
- 33,131 Subscription.party links fixed (CUST-xxx)
- 115,721 Sales Invoices (24 months) + 658K line items
- Custom field: Sales Invoice.legacy_invoice_id
- All invoices as Draft (not submitted, not sent)
Customer lifecycle preserved:
Active → services, subscriptions, invoices
Terminated → disabled=1, customer_details has departure reason/competitor
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
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