Add deposits read table (CQRS projection from bank_to_exchange events)

Project each bank_to_exchange event into a denormalized deposits table
with pre-computed EUR, DKK, and USD amounts using Frankfurter currency
rates. Replaces the aggregate get-deposit-totals query.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

resources/migrations/20260308000000-create-deposits.down.sql

@@ -0,0 +1 @@
+DROP TABLE IF EXISTS deposits;

resources/migrations/20260308000000-create-deposits.up.sql

@@ -0,0 +1,12 @@
+CREATE TABLE deposits (
+  id          BIGSERIAL PRIMARY KEY,
+  event_id    BIGINT NOT NULL REFERENCES events(id) UNIQUE,
+  occurred_at TIMESTAMPTZ NOT NULL,
+  exchange    TEXT NOT NULL,
+  fiat_amount NUMERIC(18,2) NOT NULL,
+  fiat_currency TEXT NOT NULL,
+  amount_eur  NUMERIC(18,2),
+  amount_dkk  NUMERIC(18,2),
+  amount_usd  NUMERIC(18,2),
+  note        TEXT
+);

resources/queries.sql

@@ -82,10 +82,11 @@ SELECT id, name, created_at FROM wallets WHERE id = :id
 
 -- Events --------------------------------------------------------------------
 
--- :name insert-event! :! :n
--- :doc Insert a new event
+-- :name insert-event! :? :1
+-- :doc Insert a new event, returning its id
 INSERT INTO events (event_type, occurred_at, sats, fee_sats, fiat_amount, fiat_currency, from_wallet_id, to_wallet_id, note)
 VALUES (:event-type, :occurred-at, :sats, :fee-sats, :fiat-amount, :fiat-currency, :from-wallet-id, :to-wallet-id, :note)
+RETURNING id
 
 -- :name get-all-events :? :*
 -- :doc Get all events with wallet names
@@ -125,15 +126,17 @@ LEFT JOIN wallets tw ON tw.id = e.to_wallet_id
 WHERE e.from_wallet_id = :wallet-id OR e.to_wallet_id = :wallet-id
 ORDER BY e.occurred_at DESC
 
--- :name get-deposit-totals :? :*
--- :doc Total fiat deposited per exchange per currency from bank_to_exchange events
-SELECT tw.name AS exchange, e.fiat_currency AS currency,
-       SUM(e.fiat_amount) AS total
-FROM events e
-JOIN wallets tw ON tw.id = e.to_wallet_id
-WHERE e.event_type = 'bank_to_exchange'
-GROUP BY tw.name, e.fiat_currency
-ORDER BY tw.name, e.fiat_currency
+-- :name insert-deposit! :! :n
+-- :doc Insert a projected deposit row
+INSERT INTO deposits (event_id, occurred_at, exchange, fiat_amount, fiat_currency, amount_eur, amount_dkk, amount_usd, note)
+VALUES (:event-id, :occurred-at, :exchange, :fiat-amount, :fiat-currency, :amount-eur, :amount-dkk, :amount-usd, :note)
+
+-- :name get-all-deposits :? :*
+-- :doc Get all projected deposits ordered by date descending
+SELECT id, event_id, occurred_at, exchange, fiat_amount, fiat_currency,
+       amount_eur, amount_dkk, amount_usd, note
+FROM deposits
+ORDER BY occurred_at DESC
 
 -- :name get-wallet-balances :? :*
 -- :doc Compute sats balance per wallet from events