feat: add Otterscan block explorer to dev environment (#109)

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

docker-compose.yml

@@ -213,6 +213,24 @@ services:
       retries: 3
       start_period: 2s
 
+  otterscan:
+    image: otterscan/otterscan:v2.6.0
+    environment:
+      - ERIGON_URL=http://localhost:8545
+    expose:
+      - "80"
+    ports:
+      - "127.0.0.1:5100:80"
+    restart: unless-stopped
+    networks:
+      - harb-network
+    logging: *default-logging
+    healthcheck:
+      test: ["CMD", "wget", "--spider", "-q", "http://127.0.0.1:80"]
+      interval: 5s
+      retries: 4
+      start_period: 5s
+
 volumes:
   postgres-data:
   ponder_node_modules: