Add BINANCE_ENABLED and STRIKE_ENABLED env flags

Skip live WebSocket/API connections when set to false.
Defaults to true so Docker keeps fetching.

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

resources/system.edn

@@ -52,7 +52,8 @@
 
  :ws/binance
  {:query-fn #ig/ref :db.sql/query-fn
-  :uri      "wss://stream.binance.com:9443/ws/btcusdt@trade"}
+  :uri      "wss://stream.binance.com:9443/ws/btcusdt@trade"
+  :enabled? #or [#env BINANCE_ENABLED "true"]}
 
  :kraken/ohlc
  {:query-fn #ig/ref :db.sql/query-fn}
@@ -67,4 +68,5 @@
  :strike/ticker
  {:query-fn        #ig/ref :db.sql/query-fn
   :api-key         #env STRIKE_API_KEY
-  :sats-eur-amount #or [#env SATS_EUR_AMOUNT "55"]}}
+  :sats-eur-amount #or [#env SATS_EUR_AMOUNT "55"]
+  :enabled?        #or [#env STRIKE_ENABLED "true"]}}