Add initial configuration and templates for feedstack role.

templates/nats/nats.conf.j2

@@ -0,0 +1,13 @@
+# Single-node NATS configuration for local app-to-app messaging.
+# WeatherFeeder can publish to this server without authentication.
+
+# Client connections (WeatherFeeder + consumers).
+port: 4222
+
+# HTTP monitoring endpoint.
+monitor_port: 8222
+
+# Optional persistence for future stream use.
+jetstream {
+  store_dir: "/data"
+}