ERP Shared Core

Custom finance and ledger module architecture.

The design rests on a few principles:

• Double-entry — every transaction is recorded in pairs
• Immutable posting — posted entries are never mutated
• Reversal pattern — corrections go through reversing entries rather than edits
• Polymorphic audit log — an audit trail that can attach to many kinds of entity

[PLACEHOLDER: the problem this project solves, its context, and the outcome — no source material for this in docs/05-content-brief.md. Remember: no figures, client names, or metrics.]