feat: add AI endpoint manager plugin with configuration and routing capabilities

- Introduced `ai_endpoint_mgr` plugin to manage multiple AI provider endpoints.
- Added configuration reference documentation for `config.toml`.
- Implemented endpoint loading, active endpoint switching, and model mutation.
- Included error handling for missing endpoints and configuration failures.
- Developed unit tests covering various scenarios including error paths and concurrency.

tests/smoke_test.cpp

@@ -55,6 +55,15 @@ int main()
                << "provider = \"openai\"\n"
                << "base_url = \"https://api.openai.com/v1\"\n"
                << "api_key = \"test-key\"\n"
+               << "model = \"gpt-4o\"\n"
+               << "\n"
+               << "# minimal endpoint config for ai_endpoint_mgr / 最小 endpoint 配置供 ai_endpoint_mgr 加载\n"
+               << "[endpoints]\n"
+               << "names = \"gpt4o\"\n"
+               << "\n"
+               << "[endpoint.gpt4o]\n"
+               << "provider = \"ai_openai\"\n"
+               << "api_key = \"test-key\"\n"
                << "model = \"gpt-4o\"\n";
     }
 
@@ -217,6 +226,52 @@ int main()
     // 测试 dstalk_log / Test dstalk_log
     dstalk_log(DSTALK_LOG_INFO, "Smoke test completed successfully");
 
+    // ========================================================================
+    // 测试服务查询: ai_endpoint_mgr / Test service query: ai_endpoint_mgr
+    // 验证 endpoint 加载 / 列表脱敏 / count / get_active / Verify endpoint load / list sanitization / count / get_active
+    // 不调用真实 chat 网络 / No real chat network calls
+    // ========================================================================
+    {
+        auto* ep_mgr = static_cast<const dstalk_ai_endpoint_mgr_t*>(
+            dstalk_service_query("ai_endpoint_mgr", 1));
+        if (ep_mgr) {
+            std::cout << "[OK] ai_endpoint_mgr service found\n";
+
+            // 验证 endpoint 数量 >= 1 / Verify endpoint count >= 1
+            int n = ep_mgr->count();
+            if (n >= 1) {
+                std::cout << "[OK] ai_endpoint_mgr count = " << n << "\n";
+            } else {
+                std::cerr << "[FAIL] ai_endpoint_mgr count = " << n << " (expected >= 1)\n";
+            }
+
+            // 验证 list_json 非空且不泄露 api_key / Verify list_json non-null and no api_key leak
+            char* list = ep_mgr->list_json();
+            if (list) {
+                std::string list_str(list);
+                if (list_str.find("test-key") == std::string::npos) {
+                    std::cout << "[OK] ai_endpoint_mgr list_json sanitized (no api_key leak): "
+                              << list << "\n";
+                } else {
+                    std::cerr << "[FAIL] ai_endpoint_mgr list_json leaks api_key: " << list << "\n";
+                }
+                dstalk_free(list);
+            } else {
+                std::cerr << "[FAIL] ai_endpoint_mgr list_json returned null\n";
+            }
+
+            // 验证 get_active 非空 / Verify get_active non-null
+            const char* active = ep_mgr->get_active();
+            if (active) {
+                std::cout << "[OK] ai_endpoint_mgr get_active = " << active << "\n";
+            } else {
+                std::cerr << "[FAIL] ai_endpoint_mgr get_active returned null\n";
+            }
+        } else {
+            std::cerr << "[WARN] ai_endpoint_mgr service not found\n";
+        }
+    }
+
     // ========================================================================
     // 扩展测试块 C2: null-safety / 转义边界 / tools 调用链 / session 健壮性
     // Extended test block C2: null-safety / escape boundaries / tools chain / session robustness
@@ -751,6 +806,15 @@ int main()
                   << "provider = \"openai\"\n"
                   << "base_url = \"https://api.openai.com/v1\"\n"
                   << "api_key = \"test-key\"\n"
+                  << "model = \"gpt-4o\"\n"
+                  << "\n"
+                  << "# minimal endpoint config for ai_endpoint_mgr / 最小 endpoint 配置供 ai_endpoint_mgr 加载\n"
+                  << "[endpoints]\n"
+                  << "names = \"gpt4o\"\n"
+                  << "\n"
+                  << "[endpoint.gpt4o]\n"
+                  << "provider = \"ai_openai\"\n"
+                  << "api_key = \"test-key\"\n"
                   << "model = \"gpt-4o\"\n";
             }