docs(ai): add curl quick-start to Atlas AI chat page

frontend/src/views/AiView.vue

@@ -59,6 +59,24 @@
         </div>
       </form>
     </section>
+
+    <section class="card">
+      <h2>API quick start</h2>
+      <p class="text">
+        The UI hits <code>/api/ai/chat</code> on the same host. External callers can hit the public endpoint
+        <code>https://chat.ai.bstein.dev/api/ai/chat</code>. POST JSON with a <code>message</code> and optional
+        <code>history</code>.
+      </p>
+      <pre class="mono snippet">
+curl -X POST https://chat.ai.bstein.dev/api/ai/chat \
+  -H 'content-type: application/json' \
+  -d '{"message":"hi, what is your name?"}'</pre
+      >
+      <p class="text">
+        Responses stream in the UI. API callers get either a JSON body <code>{ reply, latency_ms }</code> or a streamed text
+        body if available.
+      </p>
+    </section>
   </div>
 </template>