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>

src/clj/pmagnus/btcdata/web/routes/api.clj

@@ -173,8 +173,8 @@
    ["/events"
     {:get  (fn [req] (tx/list-events opts req))
      :post (fn [req] (tx/create-event! opts req))}]
-   ["/deposits/totals"
-    {:get (fn [req] (tx/get-deposit-totals opts req))}]])
+   ["/deposits"
+    {:get (fn [req] (tx/list-deposits opts req))}]])
 
 (defn route-data [opts]
   (merge