feat: add Zero infra — docker-compose, env vars, Dockerfile, CI workflows

- Add zero-cache service to docker-compose.yml and docker-compose.dev.yml
- Add ZERO_* env vars to docker/.env.example
- Add NEXT_PUBLIC_ZERO_CACHE_URL to surfsense_web/.env.example
- Add NEXT_PUBLIC_ZERO_CACHE_URL placeholder ARG/ENV to Dockerfile
- Add NEXT_PUBLIC_ZERO_CACHE_URL runtime substitution to docker-entrypoint.js
- Add NEXT_PUBLIC_ZERO_CACHE_URL build arg to docker-build.yml and desktop-release.yml

docker/.env.example

@@ -35,6 +35,7 @@ EMBEDDING_MODEL=sentence-transformers/all-MiniLM-L6-v2
 
 # BACKEND_PORT=8929
 # FRONTEND_PORT=3929
+# ZERO_CACHE_PORT=5929
 # SEARXNG_PORT=8888
 # FLOWER_PORT=5555
 
@@ -69,7 +70,20 @@ EMBEDDING_MODEL=sentence-transformers/all-MiniLM-L6-v2
 # NEXT_FRONTEND_URL=https://app.yourdomain.com
 # BACKEND_URL=https://api.yourdomain.com
 # NEXT_PUBLIC_FASTAPI_BACKEND_URL=https://api.yourdomain.com
+# NEXT_PUBLIC_ZERO_CACHE_URL=https://zero.yourdomain.com
 
+# ------------------------------------------------------------------------------
+# Zero-cache (real-time sync)
+# ------------------------------------------------------------------------------
+# Defaults work out of the box for Docker deployments.
+# Change ZERO_ADMIN_PASSWORD for security in production.
+
+# ZERO_ADMIN_PASSWORD=surfsense-zero-admin
+# Full override for the Zero → Postgres connection URLs.
+# Leave commented out to use the Docker-managed `db` container (default).
+# ZERO_UPSTREAM_DB=postgresql://surfsense:surfsense@db:5432/surfsense
+# ZERO_CVR_DB=postgresql://surfsense:surfsense@db:5432/surfsense
+# ZERO_CHANGE_DB=postgresql://surfsense:surfsense@db:5432/surfsense
 
 # ------------------------------------------------------------------------------
 # Database (defaults work out of the box, change for security)