Add self-contained Docker Compose stacks for pivoine.art infrastructure

Migrated 11 services from monolithic docker-compose project into independent stacks,
each with dedicated databases, minimal .env configuration, and bind-mount data volumes.

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

mailpit/compose.yml

@@ -0,0 +1,29 @@
+---
+services:
+  mailpit:
+    image: axllent/mailpit:latest
+    container_name: mailpit
+    environment:
+      TZ: ${TIMEZONE:-Europe/Amsterdam}
+      MP_SMTP_AUTH_ACCEPT_ANY: 1
+      MP_SMTP_AUTH_ALLOW_INSECURE: 1
+      MP_MAX_MESSAGES: 5000
+      MP_SMTP_RELAY_ALL: "true"
+      MP_SMTP_RELAY_HOST: ${SMTP_RELAY_HOST}
+      MP_SMTP_RELAY_PORT: ${SMTP_RELAY_PORT}
+      MP_SMTP_RELAY_USERNAME: ${SMTP_RELAY_USERNAME}
+      MP_SMTP_RELAY_PASSWORD: ${SMTP_RELAY_PASSWORD}
+      MP_SMTP_RELAY_AUTH: plain
+      MP_SMTP_RELAY_TLS: "true"
+      MP_UI_BIND_ADDR: 0.0.0.0:0
+    volumes:
+      - ../.data/mailpit:/data
+    restart: always
+    labels:
+      - "com.centurylinklabs.watchtower.enable=true"
+    networks:
+      - compose_network
+networks:
+  compose_network:
+    name: ${NETWORK_NAME}
+    external: true