refactor: export Fastify app factory for testing

- Extract route and server configuration into an exported buildApp function
- Guard server startup so importing the module does not automatically listen on port 3000
- Preserve health and readiness endpoints and loopback-only binding
- Normalize string literals to double quotes

src/server.ts

@@ -1,24 +1,30 @@
-import Fastify from 'fastify';
+import Fastify from "fastify";
 
-const app = Fastify({
+export const buildApp = () => {
+  const app = Fastify({
     logger: true,
-});
+  });
 
-app.get('/health', async () => ({
-  status: 'ok',
-}));
+  app.get("/health", async () => ({
+    status: "ok",
+  }));
 
-app.get('/ready', async () => ({
-  status: 'ready',
+  app.get("/ready", async () => ({
+    status: "ready",
     dependencies: {
-    ollama: 'not-integrated',
+      ollama: "not-integrated",
     },
-}));
+  }));
+
+  return app;
+};
 
 const start = async () => {
+  const app = buildApp();
+
   try {
     await app.listen({
-      host: '127.0.0.1',
+      host: "127.0.0.1",
       port: 3000,
     });
   } catch (error) {
@@ -27,4 +33,6 @@ const start = async () => {
   }
 };
 
-void start();
+if (import.meta.url === `file://${process.argv[1]}`) {
+  void start();
+}