Add 165 server interaction tests for Python parity

Comprehensive test coverage matching Python's test_server_interactions.py:
- TestTools, TestToolParameters, TestOutputSchema, TestContentTypes
- TestResource, TestResourceTemplates, TestResourceAnnotations
- TestPrompts, TestPromptVariations, TestMeta
- TestCapabilities, TestProgressAndNotifications, TestRootsNotification
- TestCancelledNotification, TestLogging, TestImageContent
- TestEmbeddedResource, TestToolInputValidation, TestResourceSubscribe
- TestCompletionEdgeCases, TestBatchOperations, TestTransportEdgeCases
- Unicode, pagination, large data, error handling, and edge cases

Also fixes iterator dereference bug in client.hpp when accessing
structuredContent without registered outputSchema.

Author: 0xeb

CMakeLists.txt

@@ -229,6 +229,10 @@ if(FASTMCPP_BUILD_TESTS)
   target_link_libraries(fastmcpp_server_patterns PRIVATE fastmcpp_core)
   add_test(NAME fastmcpp_server_patterns COMMAND fastmcpp_server_patterns)
 
+  add_executable(fastmcpp_server_interactions tests/server/interactions.cpp)
+  target_link_libraries(fastmcpp_server_interactions PRIVATE fastmcpp_core)
+  add_test(NAME fastmcpp_server_interactions COMMAND fastmcpp_server_interactions)
+
   add_executable(fastmcpp_client_transports tests/client/transports.cpp)
   target_link_libraries(fastmcpp_client_transports PRIVATE fastmcpp_core)
   add_test(NAME fastmcpp_client_transports COMMAND fastmcpp_client_transports)

include/fastmcpp/client/client.hpp

@@ -594,10 +594,12 @@ class Client {
       if (wrap_result && structured.contains("result")) {
         result.data = coerce_to_schema(it->second["properties"]["result"], structured["result"]);
       } else if (structured.contains("result")) {
-        result.data = coerce_to_schema(it->second.contains("properties") && it->second["properties"].contains("result")
-                                           ? it->second["properties"]["result"]
-                                           : fastmcpp::Json::object(),
-                                       structured["result"]);
+        if (it != tool_output_schemas_.end() &&
+            it->second.contains("properties") && it->second["properties"].contains("result")) {
+          result.data = coerce_to_schema(it->second["properties"]["result"], structured["result"]);
+        } else {
+          result.data = structured["result"];
+        }
       } else {
         if (it != tool_output_schemas_.end()) {
           result.data = coerce_to_schema(it->second, structured);