[WIP] Build deterministic double-entry ledger engine

[Copilot]

• Create packages/ledger/package.json
• Create packages/ledger/tsconfig.json
• Create packages/ledger/src/types.ts — accounts, postings, snapshots, balances, transfers, reconciliation types
• Create packages/ledger/src/accounts.ts — CRUD, types (asset/liability/income/expense/equity), hierarchy
• Create packages/ledger/src/postings.ts — double-entry journal entries with balance validation
• Create packages/ledger/src/balances.ts — point-in-time balance computation from postings
• Create packages/ledger/src/snapshots.ts — monthly/periodic balance snapshots
• Create packages/ledger/src/transfers.ts — internal transfer detection and creation
• Create packages/ledger/src/reconciliation.ts — compare imported transactions vs ledger state
• Create packages/ledger/src/ledger.ts — main LedgerEngine orchestrator
• Create packages/ledger/src/index.ts — public exports
• Create test/unit/ledger.test.ts — unit tests covering all acceptance criteria
• Update root package.json to include ledger in build:packages
• Update tsconfig.test.json to add path for @financialadvisor/ledger

Original prompt

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This section details on the original issue you should resolve

<issue_title>feat(ledger): deterministic double-entry ledger engine</issue_title>
<issue_description>## Summary
Build packages/ledger — the boring, deterministic core of the financial system. Double-entry bookkeeping that is always correct.

Owns

• Accounts: CRUD, types (asset/liability/income/expense), hierarchy
• Balances: Point-in-time account balances, computed from postings
• Postings: Double-entry journal entries (every transaction = debit + credit)
• Transfers: Internal transfers between accounts (detected or manual)
• Snapshots: Monthly/periodic balance snapshots for fast queries
• Reconciliation: Compare imported transactions against ledger state

Storage

Use PluresDB (or SQLite initially) with strict schema:

accounts(id, name, type, institution, currency, created_at)
postings(id, date, debit_account, credit_account, amount_cents, memo, import_session_id)
snapshots(account_id, period, balance_cents, computed_at)

Principles

• Deterministic: same inputs always produce same ledger state
• Auditable: every balance can be recomputed from postings
• No AI involvement — pure accounting logic

Acceptance

• Double-entry postings always balance
• Balance computation from postings is correct
• Snapshot generation and verification works
• Reconciliation detects mismatches</issue_description>

Comments on the Issue (you are @copilot in this section)

• Fixes feat(ledger): deterministic double-entry ledger engine #49

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[kayodebristol]

Closing this PR to enforce the 1-PR-per-repo rule. Only one Copilot PR is allowed per repository at a time. The oldest PR (#48) will be kept active.