build: fix TBB linkage for stdexec and finalize lean hpx_main headers

Author: Hackathon User

libs/CMakeLists.txt

@@ -514,6 +514,14 @@ endif()
 
 if(TARGET STDEXEC::stdexec)
   target_link_libraries(hpx_core INTERFACE STDEXEC::stdexec)
+
+  # stdexec's exec/tbb/tbb_thread_pool.hpp transitively includes
+  # <tbb/task_arena.h> which references TBB runtime symbols. Link -ltbb so the
+  # linker can resolve them.
+  find_library(TBB_LIBRARY NAMES tbb)
+  if(TBB_LIBRARY)
+    target_link_libraries(hpx_core PUBLIC ${TBB_LIBRARY})
+  endif()
 endif()
 
 if(HPX_WITH_PARCELPORT_GASNET AND GASNET_LIBRARY_DIRS)

libs/core/init_runtime_local/include/hpx/init_runtime_local/init_runtime_local.hpp

@@ -24,12 +24,11 @@
 #include <cstdint>
 #include <cstring>
 #include <functional>
-#include <iostream>
 #include <string>
 #include <utility>
 #include <vector>
 
-// Forward declarations — replaces sub-module includes to satisfy C++20
+// Forward declarations -- replaces sub-module includes to satisfy C++20
 // module boundary requirements. Full definitions are available in the
 // corresponding .cpp files via their umbrella module includes.
 namespace hpx {

libs/full/init_runtime/include/hpx/hpx_init_params.hpp

@@ -22,7 +22,7 @@
 #include <string>
 #include <vector>
 
-// Forward declaration — replaces sub-module includes to satisfy C++20
+// Forward declaration -- replaces sub-module includes to satisfy C++20
 // module boundary requirements.
 namespace hpx {
 

libs/full/init_runtime/include/hpx/hpx_user_main_config.hpp

@@ -1,4 +1,4 @@
-//  Copyright (c) 2007-2025 Hartmut Kaiser
+//  Copyright (c) 2007-2055 Hartmut Kaiser
 //
 //  SPDX-License-Identifier: BSL-1.0
 //  Distributed under the Boost Software License, Version 1.0. (See accompanying