Address architecture + stability review (todo §0): wire buildContext, graceful shutdown, prod template caching

src/server.ts

@@ -3,6 +3,11 @@ import { loadConfig } from "./config.ts";
 
 const { port } = loadConfig(); // validates the env (incl. prod secrets) — fails loud at boot
 
-createApp().listen(port, () => {
+const server = createApp().listen(port, () => {
   console.log(`Listening on http://localhost:${port}`);
 });
+
+// Drain in-flight requests on container stop instead of cutting them mid-response.
+for (const signal of ["SIGINT", "SIGTERM"] as const) {
+  process.on(signal, () => server.close(() => process.exit(0)));
+}