feat: storage schema — import sessions, canonical transactions, merchant tables

[Copilot]

Implements the full persistence schema described in the issue: nine database-aligned tables with in-memory stores (PluresDB/SQLite-ready via migration hooks), enforcing the core invariants of immutable raw data and append-only audit trail.

New package: packages/storage

Schema types (schema.ts) — one readonly interface per table, amounts as integer cents throughout:
ImportSessionRecord, RawTransactionRecord, CanonicalTransactionRecord, MerchantRecord, MerchantAliasRecord, AccountRecord, PostingRecord, RecurringSeriesRecord, ReviewDecisionRecord

Store implementations — one class per table:

• RawTransactionStore — insert()-only; throws on duplicate id. No update/delete exposed.
• ReviewDecisionStore — record()-only; throws on duplicate id. Full history queryable by entity.
• ImportSessionStore — secondary index on fileHash for idempotent re-import detection.
• CanonicalTransactionStore — update() for reviewer decisions (reviewed, category, merchantId, confidence); raw-tx uniqueness enforced.
• MerchantAliasStore — supports exact | prefix | contains | regex match types.
• PostingStore — date-range and canonical-transaction lookups.
• RecurringSeriesStore — status/merchant/account filters with partial update().

Migration layer

MigrationRunner tracks applied versions and runs them in order, skipping already-applied ones. SCHEMA_MIGRATIONS ships v1 (all 9 tables) as a no-op for in-memory — the apply() hook is the integration point for future DDL:

// Ready for PluresDB/SQLite DDL — just fill in apply():
{ version: 1, description: 'Initial schema: import_sessions, ...', async apply() { /* CREATE TABLE ... */ } }

Factory

createStorageSchema() runs migrations then returns all stores as a typed StorageSchema — one instance per logical DB context.

const schema = await createStorageSchema();
schema.rawTransactions.insert(rawTx);                          // immutable
schema.canonicalTransactions.update(id, { reviewed: true });   // canonical layer
schema.reviewDecisions.record({ ...decision });                // audit trail

Build wiring

packages/storage added to build:packages (after domain) and to all test copy/mkdir steps in root package.json.

Original prompt

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This section details on the original issue you should resolve

<issue_title>feat: storage schema — import sessions, canonical transactions, merchant tables</issue_title>
<issue_description>## Summary
Design and implement the storage schema that underpins the entire application. Current storage is likely too shallow.

Schema

-- Import provenance
import_sessions(id, file_hash, filename, account_id, imported_at, total_rows, parsed_rows, error_rows)

-- Raw imported data (never modified)
raw_transactions(id, import_session_id, row_number, date, amount_cents, description, raw_data_json)

-- Resolved/canonical transactions
canonical_transactions(id, raw_transaction_id, date, amount_cents, merchant_id, category, confidence, reviewed)

-- Merchant resolution
merchants(id, canonical_name, category, created_at, updated_at)
merchant_aliases(id, merchant_id, alias_pattern, match_type, created_by)

-- Double-entry ledger
accounts(id, name, type, institution, currency, created_at)
postings(id, date, debit_account_id, credit_account_id, amount_cents, canonical_transaction_id, memo)

-- Recurring detection
recurring_series(id, merchant_id, account_id, interval_days, avg_amount_cents, confidence, status)

-- Review decisions
review_decisions(id, entity_type, entity_id, decision, decided_at, previous_value, new_value)

Principles

• Raw data is immutable — never modify imported rows
• All mutations go through canonical layer
• Every decision is logged in review_decisions
• Use PluresDB if available, SQLite as fallback

Acceptance

• Schema implemented with migrations
• Raw transactions preserved immutably
• All CRUD operations tested
• Review decisions create audit trail</issue_description>

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

• Fixes feat: storage schema — import sessions, canonical transactions, merchant tables #66

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