Add Strike ticker poller, Docker .env config, and Frankfurter retry logic

- Poll Strike API every 10s, store all rates as JSONB in strike_price table
- Move Docker env vars to .env file, use shared network for cross-project communication
- Add startup retry (5x 5s) for Frankfurter poller to handle container race condition

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

resources/system.edn

@@ -60,4 +60,8 @@
  {:query-fn #ig/ref :db.sql/query-fn}
 
  :frankfurter/rates
- {:url #or [#env FRANKFURTER_URL "http://localhost:8080"]}}
+ {:url #or [#env FRANKFURTER_URL "http://localhost:8080"]}
+
+ :strike/ticker
+ {:query-fn #ig/ref :db.sql/query-fn
+  :api-key  #env STRIKE_API_KEY}}