Bump Docker base images: MySQL 8.0.46, nginx 1.30.2-alpine

Also moves nginx from mainline (1.29.x) to the stable branch (1.30.x).

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

docker-compose.yml

@@ -4,7 +4,7 @@ services:
   # MYSQL_ROOT_PASSWORD and MYSQL_PASSWORD should each be 20+ random characters.
   # Generate with: openssl rand -hex 16
   db:
-    image: mysql:8.0.45
+    image: mysql:8.0.46
     restart: unless-stopped
     deploy:
       resources:
@@ -70,7 +70,7 @@ services:
 
   # ── Nginx ────────────────────────────────────────────────────────────────────
   nginx:
-    image: nginx:1.29.6-alpine
+    image: nginx:1.30.2-alpine
     restart: unless-stopped
     deploy:
       resources: