W22: coverage metric + network tests + Tool stream feedback + stdin pipe + session path + dependency check (W22.1-W22.6)

- W22.1: gcovr 覆盖率度量 + CI coverage job（40% 阈值 warning）
- W22.2: network_plugin 单元测试（parse_headers_json/extract_host_port/SSE/异常保护）
- W22.3: Tool Calling 流式反馈（chat_stream + "[工具调用]/[工具结果]" 状态行）
- W22.4: --prompt stdin pipe（--prompt - 从 stdin 读取）
- W22.5: session 路径健壮化（static 缓存 + mkdir + fallback）
- W22.6: 插件依赖拓扑静态校验（validate_dependencies 循环/缺失检测）

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

tests/CMakeLists.txt

@@ -177,3 +177,71 @@ target_link_libraries(dstalk-deepseek-plugin-test
 )
 
 add_test(NAME dstalk-deepseek-plugin-test COMMAND dstalk-deepseek-plugin-test)
+
+# ============================================================
+# dstalk-network-plugin-test — Network 插件单元测试
+# W22.2 (qa-xu): 通过 #include source 访问 static 函数
+# ============================================================
+
+find_package(OpenSSL REQUIRED CONFIG)
+
+add_executable(dstalk-network-plugin-test
+    network_plugin_test.cpp
+)
+
+target_include_directories(dstalk-network-plugin-test
+    PRIVATE ${CMAKE_SOURCE_DIR}/dstalk-core/include
+)
+
+target_compile_definitions(dstalk-network-plugin-test
+    PRIVATE
+        BOOST_ALL_NO_LIB
+)
+
+target_link_libraries(dstalk-network-plugin-test
+    PRIVATE
+        dstalk
+        boost::boost
+        openssl::openssl
+)
+
+add_test(NAME dstalk-network-plugin-test COMMAND dstalk-network-plugin-test)
+
+# ============================================================
+# coverage — gcovr 覆盖率报告 (HTML + 终端摘要)
+# 用法: cmake --build <dir> --target coverage
+# 前提: 已用 --coverage flag 构建并通过 ctest 运行测试
+# ============================================================
+
+find_program(GCOVR_EXECUTABLE gcovr)
+find_program(GCOV_EXECUTABLE gcov)
+find_program(LLVM_COV_EXECUTABLE llvm-cov-18 llvm-cov)
+
+if(GCOVR_EXECUTABLE)
+    if(LLVM_COV_EXECUTABLE)
+        set(GCOV_CMD "${LLVM_COV_EXECUTABLE} gcov")
+    elseif(GCOV_EXECUTABLE)
+        set(GCOV_CMD "${GCOV_EXECUTABLE}")
+    else()
+        set(GCOV_CMD "")
+    endif()
+
+    add_custom_target(coverage
+        COMMAND ${GCOVR_EXECUTABLE} -r ${CMAKE_SOURCE_DIR}
+            --object-directory=${CMAKE_BINARY_DIR}
+            --gcov-executable "${GCOV_CMD}"
+            --print-summary
+        COMMAND ${GCOVR_EXECUTABLE} -r ${CMAKE_SOURCE_DIR}
+            --object-directory=${CMAKE_BINARY_DIR}
+            --gcov-executable "${GCOV_CMD}"
+            --html --html-details
+            -o ${CMAKE_BINARY_DIR}/coverage/index.html
+        COMMENT "Coverage: HTML report -> ${CMAKE_BINARY_DIR}/coverage/index.html"
+        WORKING_DIRECTORY ${CMAKE_BINARY_DIR}
+    )
+else()
+    add_custom_target(coverage
+        COMMAND ${CMAKE_COMMAND} -E echo "gcovr not found. Install: pip install gcovr"
+        COMMENT "Coverage target unavailable (gcovr not found)"
+    )
+endif()