Implement Tink transaction enrichment with merchant data and personal finance category for PFM integration

Steps

1. Complete Tink Link initialization with the transactions:read scope and obtain a Tink user access token via the authorization code exchange flow
2. Fetch raw transactions from the Tink Transactions API; the response includes a categories field with Tink's taxonomy code and a merchant object with enriched merchant name, MCC, and logo URL when available
3. Subscribe to the transaction:updated webhook event to receive enrichment updates asynchronously — Tink may enrich a transaction after initial fetch as its enrichment pipeline processes the data
4. Map Tink's category taxonomy to your own PFM category hierarchy; store the mapping table versioned so future taxonomy changes can be re-applied to historical data
5. For transactions where merchant enrichment is absent (common for P2P payments and bank fees), implement a fallback rule set based on transaction description pattern matching
6. Aggregate categorized transaction data by time period to compute budget and spending trend metrics; use Tink's account balance history endpoint to validate that your transaction aggregation matches the account's reported balance