feat: add ProxCenter swarm stack draft

proxcenter.env.example

@@ -0,0 +1,54 @@
+# ProxCenter Community Edition — Environment Variables
+# Copy to proxcenter.env and fill in real values before deploying.
+# Usage:
+#   cp proxcenter.env.example proxcenter.env
+#   edit proxcenter.env
+#   set -a; . ./proxcenter.env; set +a
+#   docker stack deploy -c proxcenter-compose.yml proxcenter
+#
+# Docker stack deploy does not support --env-file directly. If you do not
+# want to source the env file, render the stack first:
+#   docker compose --env-file proxcenter.env -f proxcenter-compose.yml config \
+#     | docker stack deploy -c - proxcenter
+#
+# NEVER commit the real proxcenter.env file. Only commit this example.
+
+# ========================================
+# Image version pinning (optional)
+# ========================================
+# Leave commented to use the latest tag, or pin to a specific release:
+# VERSION=1.2.3
+VERSION=latest
+
+# ========================================
+# Application URLs
+# ========================================
+# Public-facing URL of your ProxCenter instance.
+# Used for NextAuth callbacks, redirects, and link generation.
+NEXTAUTH_URL=https://proxcenter.example.com
+APP_URL=https://proxcenter.example.com
+
+# ========================================
+# Security secrets (required)
+# ========================================
+# Generate strong random values:
+#   openssl rand -base64 32
+#
+# Docker Secrets alternative: instead of setting these here, create
+# Docker Swarm secrets and use APP_SECRET_FILE / NEXTAUTH_SECRET_FILE
+# in the compose file. See comments in proxcenter-compose.yml.
+APP_SECRET=change-me-generate-with-openssl-rand-base64-32
+NEXTAUTH_SECRET=change-me-generate-with-openssl-rand-base64-32
+
+# ========================================
+# Postgres credentials (required)
+# ========================================
+# These are used by both the postgres service (to initialise the DB)
+# and the frontend service (to build the DATABASE_URL connection string).
+POSTGRES_USER=proxcenter
+POSTGRES_PASSWORD=change-me-use-a-strong-password
+POSTGRES_DB=proxcenter
+
+# DATABASE_URL is built automatically from the variables above.
+# Override only if pointing the frontend at an external Postgres instance:
+# DATABASE_URL=postgresql://proxcenter:password@external-host:5432/proxcenter?schema=public