Add auth system, fix map defaults, controls overflow, fix latest-date ref

stack.env.example

@@ -0,0 +1,12 @@
+# OSM Import Tools – environment configuration
+# Edit these values before deploying. In Portainer GitOps you can also
+# override them in the stack's Environment Variables UI.
+
+# Password for the built-in 'admin' account.
+# The container seeds this on every startup, so changing it here
+# and redeploying will update the password automatically.
+ADMIN_PASSWORD=changeme
+
+# Secret key for Flask session signing.
+# Generate a strong random value, e.g.:  python -c "import secrets; print(secrets.token_hex(32))"
+FLASK_SECRET_KEY=change-this-to-a-long-random-string