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.

dstalk_gui/CMakeLists.txt

@@ -0,0 +1,16 @@
+# ============================================================
+# dstalk_gui — 图形化前端 (SDL3)
+# ============================================================
+
+# 启用 DSTALK_BUILD_GUI=ON 前，确保 deps/conanfile.txt 中包含 sdl 依赖
+find_package(SDL3 REQUIRED CONFIG)
+
+add_executable(dstalk_gui
+    src/main.cpp
+)
+
+target_link_libraries(dstalk_gui
+    PRIVATE
+        dstalk
+        SDL3::SDL3
+)