fix: increase db healthcheck start_period to 360s for first-boot init

MySQL first-boot InnoDB init + schema.sql takes ~6 minutes.
Previous config only allowed 130s total (30s start_period + 20x5s),
causing container to be marked unhealthy before MySQL was ready.

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

docker-compose.yaml

@@ -37,10 +37,10 @@ services:
       - mysql-data:/var/lib/mysql
     healthcheck:
       test: ["CMD-SHELL", "mysqladmin ping -h localhost -uroot -p\"$${MYSQL_ROOT_PASSWORD}\" --silent"]
-      interval: 5s
+      interval: 10s
       timeout: 5s
-      retries: 20
+      retries: 30
-      start_period: 30s
+      start_period: 360s
 
 volumes:
   mysql-data: