feat(ms22-p2): add agent selector UI in WebUI (#685)

Co-authored-by: Jason Woltje <jason@diversecanvas.com>
Co-committed-by: Jason Woltje <jason@diversecanvas.com>

apps/web/src/lib/api/chat.ts

@@ -18,6 +18,7 @@ export interface ChatRequest {
   temperature?: number;
   maxTokens?: number;
   systemPrompt?: string;
+  agent?: string;
 }
 
 export interface ChatResponse {
@@ -117,7 +118,11 @@ export function streamGuestChat(
           "Content-Type": "application/json",
         },
         credentials: "include",
-        body: JSON.stringify({ messages: request.messages, stream: true }),
+        body: JSON.stringify({
+          messages: request.messages,
+          stream: true,
+          ...(request.agent && { agent: request.agent }),
+        }),
         signal: signal ?? null,
       });
 
@@ -269,7 +274,11 @@ export function streamChatMessage(
           "X-CSRF-Token": csrfToken,
         },
         credentials: "include",
-        body: JSON.stringify({ messages: request.messages, stream: true }),
+        body: JSON.stringify({
+          messages: request.messages,
+          stream: true,
+          ...(request.agent && { agent: request.agent }),
+        }),
         signal: signal ?? null,
       });