feat: add mas-db postgres for matrix authentication service

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

compose/hf-pdocker-01/mas/docker-compose.yml

@@ -0,0 +1,33 @@
+services:
+  mas-db:
+    image: postgres:16-alpine
+    container_name: mas-db
+    restart: unless-stopped
+    environment:
+      - POSTGRES_USER=mas
+      - POSTGRES_PASSWORD=3XRBtczkPrdbNgdJftKGWu7QwhT3
+      - POSTGRES_DB=mas
+    volumes:
+      # LOCAL disk, never NFS (Known Issue #16)
+      - /var/lib/mas-db:/var/lib/postgresql/data
+    networks:
+      - mas
+    mem_limit: 256M
+    memswap_limit: 256M
+    labels:
+      - "com.centurylinklabs.watchtower.enable=false"
+    healthcheck:
+      test: ["CMD-SHELL", "pg_isready -U mas -d mas"]
+      interval: 30s
+      timeout: 10s
+      retries: 3
+      start_period: 30s
+    logging:
+      driver: "json-file"
+      options:
+        max-size: "50m"
+        max-file: "3"
+
+networks:
+  mas:
+    driver: bridge