Refactor AssistantPage to streamline agent platform handling

- Remove the draftAgentPlatform state and related logic, simplifying the creation process for assistant types.
- Default the agent platform to "dify" when creating an assistant of type "智能体平台".
- Replace the platform selection buttons with a ResourceSelectField for improved user experience and maintainability.
- Update the confirmType function to reflect the changes in platform handling.

frontend/src/components/pages/AssistantPage.tsx

@@ -314,8 +314,6 @@ export function AssistantPage(props: AssistantPageProps) {
   // (工作流占位页也用它展示名称与类型)
   const [draftName, setDraftName] = useState("");
   const [draftType, setDraftType] = useState<BuildMethod | null>(null);
-  const [draftAgentPlatform, setDraftAgentPlatform] =
-    useState<AgentPlatform | null>(null);
   // 引导页:创建请求进行中 / 创建失败
   const [creating, setCreating] = useState(false);
   const [createError, setCreateError] = useState<string | null>(null);
@@ -480,26 +478,19 @@ export function AssistantPage(props: AssistantPageProps) {
   }
 
   // 引导页确认：直接创建到数据库拿到 id，再进入该助手的编辑页
+  // 智能体平台默认先建 dify，具体平台在编辑页再选
   async function confirmType() {
-    if (
-      !draftName.trim() ||
-      !draftType ||
-      (draftType === "智能体平台" && !draftAgentPlatform) ||
-      creating
-    ) {
+    if (!draftName.trim() || !draftType || creating) {
       return;
     }
 
     setCreating(true);
     setCreateError(null);
     try {
-      let assistantType: ApiAssistantType;
-      if (draftType === "智能体平台") {
-        if (!draftAgentPlatform) return;
-        assistantType = draftAgentPlatform;
-      } else {
-        assistantType = typeFromBuildMethod[draftType];
-      }
+      const assistantType: ApiAssistantType =
+        draftType === "智能体平台"
+          ? "dify"
+          : typeFromBuildMethod[draftType];
       const created = await assistantsApi.create(
         baseUpsert({
           name: draftName.trim(),
@@ -1228,40 +1219,6 @@ export function AssistantPage(props: AssistantPageProps) {
               );
             })}
           </div>
-
-          {draftType === "智能体平台" && (
-            <div className="rounded-2xl border border-hairline bg-card p-5">
-              <div className="text-sm font-medium text-foreground">
-                选择智能体平台
-              </div>
-              <p className="mt-1.5 text-sm leading-6 text-muted-foreground">
-                平台类型用于匹配对应的应用资源和运行方式。
-              </p>
-              <div className="mt-4 flex flex-wrap gap-3">
-                {(["dify", "fastgpt"] as const).map((platform) => {
-                  const selected = draftAgentPlatform === platform;
-                  const label = platform === "dify" ? "Dify" : "FastGPT";
-
-                  return (
-                    <Button
-                      key={platform}
-                      type="button"
-                      variant={selected ? "default" : "outline"}
-                      className={
-                        selected
-                          ? "gap-2"
-                          : "gap-2 border-hairline-strong text-muted-foreground hover:text-foreground"
-                      }
-                      onClick={() => setDraftAgentPlatform(platform)}
-                    >
-                      {selected && <Check size={14} />}
-                      {label}
-                    </Button>
-                  );
-                })}
-              </div>
-            </div>
-          )}
         </section>
 
         <div className="flex items-center justify-end gap-3">
@@ -1280,12 +1237,7 @@ export function AssistantPage(props: AssistantPageProps) {
           <Button
             size="lg"
             className="gap-2"
-            disabled={
-              !draftName.trim() ||
-              !draftType ||
-              (draftType === "智能体平台" && !draftAgentPlatform) ||
-              creating
-            }
+            disabled={!draftName.trim() || !draftType || creating}
             onClick={() => void confirmType()}
           >
             {creating ? (
@@ -1395,35 +1347,17 @@ export function AssistantPage(props: AssistantPageProps) {
               title="智能体平台配置"
               description={`选择智能体平台及对应应用。开场白、知识库、提示词等对话编排请在 ${platformLabel} 平台配置，本页不重复设置。`}
             >
-              <div>
-                <div className="mb-2 text-sm font-medium text-foreground">
-                  智能体平台
-                </div>
-                <div className="flex flex-wrap gap-2">
-                  {(["dify", "fastgpt"] as const).map((platform) => {
-                    const selected = agentPlatformForm.platform === platform;
-                    const label = platform === "dify" ? "Dify" : "FastGPT";
-
-                    return (
-                      <Button
-                        key={platform}
-                        type="button"
-                        size="sm"
-                        variant={selected ? "default" : "outline"}
-                        className={
-                          selected
-                            ? "gap-2"
-                            : "gap-2 border-hairline-strong text-muted-foreground hover:text-foreground"
-                        }
-                        onClick={() => handleAgentPlatformChange(platform)}
-                      >
-                        {selected && <Check size={14} />}
-                        {label}
-                      </Button>
-                    );
-                  })}
-                </div>
-              </div>
+              <ResourceSelectField
+                label="智能体平台"
+                value={agentPlatformForm.platform}
+                onChange={(value) =>
+                  handleAgentPlatformChange(value as AgentPlatform)
+                }
+                options={[
+                  { value: "dify", label: "Dify" },
+                  { value: "fastgpt", label: "FastGPT" },
+                ]}
+              />
               <ResourceSelectField
                 label={`${platformLabel} 应用`}
                 value={agentPlatformForm.agent}