[fix] Droid: dynamic x-api-provider and custom User-Agent support

- Dynamic x-api-provider selection for OpenAI endpoint based on model
  - Models with '-max' suffix use 'openai' provider
  - Other models use 'azure_openai' provider
  - Fixes gpt-5.1-codex-max model compatibility issue

- Update default User-Agent to factory-cli/0.32.1

- Add custom User-Agent field for Droid accounts
  - Backend: userAgent field in createAccount and updateAccount
  - Frontend: User-Agent input in account creation/edit UI
  - Supports all Droid auth modes: OAuth, Manual, API Key

This resolves the issue where gpt-5.1-codex-max failed with 'Azure OpenAI only supports...' error due to incorrect provider header.

web/admin-spa/src/components/accounts/AccountForm.vue

@@ -1944,6 +1944,22 @@
                   rows="4"
                 />
               </div>
+
+              <!-- Droid User-Agent 配置 (OAuth/Manual 模式) -->
+              <div v-if="form.platform === 'droid'">
+                <label class="mb-3 block text-sm font-semibold text-gray-700 dark:text-gray-300"
+                  >自定义 User-Agent (可选)</label
+                >
+                <input
+                  v-model="form.userAgent"
+                  class="form-input w-full border-gray-300 dark:border-gray-600 dark:bg-gray-700 dark:text-gray-200 dark:placeholder-gray-400"
+                  placeholder="factory-cli/0.32.1"
+                  type="text"
+                />
+                <p class="mt-1 text-xs text-gray-500 dark:text-gray-400">
+                  留空使用默认值 factory-cli/0.32.1，可根据需要自定义
+                </p>
+              </div>
             </div>
 
             <!-- API Key 模式输入 -->
@@ -1989,6 +2005,22 @@
                 </p>
               </div>
 
+              <!-- Droid User-Agent 配置 -->
+              <div>
+                <label class="mb-3 block text-sm font-semibold text-gray-700 dark:text-gray-300"
+                  >自定义 User-Agent (可选)</label
+                >
+                <input
+                  v-model="form.userAgent"
+                  class="form-input w-full border-gray-300 dark:border-gray-600 dark:bg-gray-700 dark:text-gray-200 dark:placeholder-gray-400"
+                  placeholder="factory-cli/0.32.1"
+                  type="text"
+                />
+                <p class="mt-1 text-xs text-gray-500 dark:text-gray-400">
+                  留空使用默认值 factory-cli/0.32.1，可根据需要自定义
+                </p>
+              </div>
+
               <div
                 class="rounded-lg border border-purple-200 bg-white/70 p-3 text-xs text-purple-800 dark:border-purple-700 dark:bg-purple-800/20 dark:text-purple-100"
               >
@@ -3639,6 +3671,22 @@
             </div>
           </div>
 
+          <!-- Droid User-Agent 配置 (编辑模式) -->
+          <div v-if="form.platform === 'droid'">
+            <label class="mb-3 block text-sm font-semibold text-gray-700 dark:text-gray-300"
+              >自定义 User-Agent (可选)</label
+            >
+            <input
+              v-model="form.userAgent"
+              class="form-input w-full border-gray-300 dark:border-gray-600 dark:bg-gray-700 dark:text-gray-200 dark:placeholder-gray-400"
+              placeholder="factory-cli/0.32.1"
+              type="text"
+            />
+            <p class="mt-1 text-xs text-gray-500 dark:text-gray-400">
+              留空使用默认值 factory-cli/0.32.1，可根据需要自定义
+            </p>
+          </div>
+
           <!-- 代理设置 -->
           <ProxyConfig v-model="form.proxy" />