feat: add OpenAI-compatible AI provider plugin with SSE streaming support

- Implemented the OpenAI-compatible AI provider plugin, including configuration, chat, and chat_stream functionalities.
- Added support for SSE streaming and tool calls.
- Integrated Boost.JSON for JSON handling.
- Created CMake configuration for the plugin.
- Added error handling and logging throughout the plugin.

CMakeLists.txt

@@ -11,16 +11,19 @@ option(DSTALK_BUILD_GUI "Build the SDL3 GUI frontend" OFF)
 option(DSTALK_BUILD_WEB "Build the web UI frontend" OFF)
 option(DSTALK_BUILD_TESTS "Build dstalk tests" ON)
 
-add_subdirectory(dstalk-core)
-add_subdirectory(dstalk-cli)
-add_subdirectory(plugins)
+add_subdirectory(dstalk_core)
+add_subdirectory(dstalk_cli)
+# 插件按依赖层级分三个目录 / Plugins split into three directories by dependency tier
+add_subdirectory(plugins_base)
+add_subdirectory(plugins_middle)
+add_subdirectory(plugins_upper)
 
 if(DSTALK_BUILD_GUI)
-    add_subdirectory(dstalk-gui)
+    add_subdirectory(dstalk_gui)
 endif()
 
 if(DSTALK_BUILD_WEB)
-    add_subdirectory(dstalk-web)
+    add_subdirectory(dstalk_web)
 endif()
 
 if(DSTALK_BUILD_TESTS)