fix: resolve CI failures for S3 endpoint and template deduction

1. ConfigureS3Options now falls back to AWS_ENDPOINT_URL_S3 and
   AWS_ENDPOINT_URL environment variables when the endpoint is not
   specified in properties, matching Arrow's S3Options::FromUri behavior.
   This fixes macOS CI where MinIO endpoint was not being picked up.

2. Wrap string literals with std::string() in rest_catalog_integration_test
   to fix template argument deduction failure in ConfigBase::Set() on GCC.

Generated with [Claude Code](https://claude.ai/code)
via [Happy](https://happy.engineering)

Co-Authored-By: Claude <noreply@anthropic.com>
Co-Authored-By: Happy <yesreply@happy.engineering>

Author: 3 people

src/iceberg/arrow/arrow_s3_file_io.cc

@@ -17,6 +17,7 @@
  * under the License.
  */
 
+#include <cstdlib>
 #include <mutex>
 #include <stdexcept>
 
@@ -93,6 +94,17 @@ Result<::arrow::fs::S3Options> ConfigureS3Options(
   auto endpoint_it = properties.find(S3Properties::kEndpoint);
   if (endpoint_it != properties.end()) {
     options.endpoint_override = endpoint_it->second;
+  } else {
+    // Fall back to AWS standard environment variables for endpoint override
+    const char* s3_endpoint_env = std::getenv("AWS_ENDPOINT_URL_S3");
+    if (s3_endpoint_env != nullptr) {
+      options.endpoint_override = s3_endpoint_env;
+    } else {
+      const char* endpoint_env = std::getenv("AWS_ENDPOINT_URL");
+      if (endpoint_env != nullptr) {
+        options.endpoint_override = endpoint_env;
+      }
+    }
   }
 
   auto path_style_it = properties.find(S3Properties::kPathStyleAccess);

src/iceberg/test/rest_catalog_integration_test.cc

@@ -497,7 +497,7 @@ TEST_F(RestCatalogIntegrationTest, MakeWithUnregisteredIoImplReturnsError) {
   auto config = RestCatalogProperties::default_properties();
   config.Set(RestCatalogProperties::kUri, CatalogUri())
       .Set(RestCatalogProperties::kName, std::string(kCatalogName))
-      .Set(RestCatalogProperties::kWarehouse, "/local/warehouse");
+      .Set(RestCatalogProperties::kWarehouse, std::string("/local/warehouse"));
   config.mutable_configs()[FileIOProperties::kImpl] = "com.nonexistent.FileIO";
 
   auto result = RestCatalog::Make(config);
@@ -519,7 +519,7 @@ TEST_F(RestCatalogIntegrationTest, MakeWithAutoDetectedLocalFileIO) {
   auto config = RestCatalogProperties::default_properties();
   config.Set(RestCatalogProperties::kUri, CatalogUri())
       .Set(RestCatalogProperties::kName, std::string(kCatalogName))
-      .Set(RestCatalogProperties::kWarehouse, "/local/warehouse");
+      .Set(RestCatalogProperties::kWarehouse, std::string("/local/warehouse"));
 
   auto catalog_result = RestCatalog::Make(config);
   ASSERT_THAT(catalog_result, IsOk());
@@ -541,7 +541,7 @@ TEST_F(RestCatalogIntegrationTest, MakeWithCustomIoImpl) {
   auto config = RestCatalogProperties::default_properties();
   config.Set(RestCatalogProperties::kUri, CatalogUri())
       .Set(RestCatalogProperties::kName, std::string(kCatalogName))
-      .Set(RestCatalogProperties::kWarehouse, "/any/warehouse");
+      .Set(RestCatalogProperties::kWarehouse, std::string("/any/warehouse"));
   config.mutable_configs()[FileIOProperties::kImpl] = custom_impl;
 
   auto catalog_result = RestCatalog::Make(config);