feat: Initial minimal docker compose and updates to release workflows.

docker/example.env

@@ -0,0 +1,20 @@
+# Shared with database & app
+POSTGRES_USER=ductcalc
+POSTGRES_PASSWORD=super-secret-change-me
+POSTGRES_DB=ductcalc
+
+# App only
+#
+POSTGRES_HOSTNAME=db
+
+# If using sqlite not postgres
+#SQLITE_PATH=db.sqlite
+
+# Set the pdf engine to use, this generally does not
+# need set, unless extending the base image.
+#PDF_ENGINE=weasyprint
+
+# Set the path to the pandoc executable. This generally
+# does not need set, unless extending the base image.
+#PANDOC_PATH=/usr/bin/pandoc
+