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>

docker-compose.yml

@@ -1,16 +1,25 @@
+networks:
+  shared:
+    name: shared
+    external: true
+
 services:
   btcdata:
     build: .
     restart: unless-stopped
     ports:
-      - "4101:4101"
+      - "${DOCKER_BTCDATA_PORT}:${DOCKER_BTCDATA_PORT}"
     depends_on:
       - frankfurter
+    networks:
+      - default
+      - shared
     environment:
-      BTCDATA_PORT: "4101"
-      JDBC_URL: "jdbc:postgresql://postgres:5432/btcprod?user=postgres&password=ratata,123"
-      CORS_ORIGIN: "http://localhost:4041"
-      FRANKFURTER_URL: "http://frankfurter:8080"
+      BTCDATA_PORT: "${DOCKER_BTCDATA_PORT}"
+      JDBC_URL: "${DOCKER_JDBC_URL}"
+      CORS_ORIGIN: "${DOCKER_CORS_ORIGIN}"
+      FRANKFURTER_URL: "${DOCKER_FRANKFURTER_URL}"
+      STRIKE_API_KEY: "${STRIKE_API_KEY}"
     extra_hosts:
       - "postgres:host-gateway"