Persist chat history to Postgres via durable JetStream consumer

DATABASE_URL required at startup; schema self-initializes.
Compose gains a postgres service for standalone dev.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

src/main.rs

@@ -10,7 +10,7 @@ async fn main() -> anyhow::Result<()> {
         Router,
     };
     use cnats::app::{shell, App};
-    use cnats::server::{oidc, sse, AppState};
+    use cnats::server::{oidc, sse, store, AppState};
     use leptos::prelude::*;
     use leptos_axum::{generate_route_list, LeptosRoutes};
     use std::sync::Arc;
@@ -34,12 +34,25 @@ async fn main() -> anyhow::Result<()> {
     tracing::info!(%nats_url, "connecting to NATS");
     let nats = async_nats::connect(&nats_url).await?;
 
+    let database_url = std::env::var("DATABASE_URL")
+        .unwrap_or_else(|_| "postgres://cnats:cnats@127.0.0.1:5432/cnats".to_string());
+    tracing::info!("connecting to postgres");
+    let pool = sqlx::postgres::PgPoolOptions::new()
+        .max_connections(5)
+        .connect(&database_url)
+        .await?;
+    store::init_schema(&pool).await?;
+
+    // Archive chat.room.* into Postgres via a durable JetStream consumer.
+    tokio::spawn(store::run_consumer(nats.clone(), pool.clone()));
+
     let oidc_state = Arc::new(oidc::Oidc::from_env().await?);
 
     let state = AppState {
         leptos_options: leptos_options.clone(),
         nats,
         oidc: oidc_state,
+        pool,
     };
 
     // Dev-friendly defaults: in-memory sessions, secure cookies only when