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.

plugins_base/lsp/CMakeLists.txt

@@ -0,0 +1,28 @@
+cmake_minimum_required(VERSION 3.21)
+
+# ============================================================
+# plugin-lsp — LSP (Language Server Protocol) 服务
+# 自行管理子进程，无外部服务依赖
+# ============================================================
+
+add_library(plugin-lsp SHARED
+    src/lsp_plugin.cpp
+)
+
+target_link_libraries(plugin-lsp PRIVATE dstalk)
+
+# Boost.JSON 用于 JSON-RPC 消息构建/解析
+find_package(Boost REQUIRED CONFIG)
+target_link_libraries(plugin-lsp PRIVATE boost::boost dstalk_boost_config)
+
+# POSIX 平台需要 pthread (用于 std::thread)
+if(NOT WIN32)
+    find_package(Threads REQUIRED)
+    target_link_libraries(plugin-lsp PRIVATE Threads::Threads)
+endif()
+
+set_target_properties(plugin-lsp PROPERTIES
+    PREFIX ""
+    LIBRARY_OUTPUT_DIRECTORY "${CMAKE_BINARY_DIR}/plugins"
+    RUNTIME_OUTPUT_DIRECTORY "${CMAKE_BINARY_DIR}/plugins"
+)