Add Missing Includes Across src/slic3r/GUI (#16048)

* Add Missing Includes Across src/slic3r/GUI

Every GUI source and header now directly includes the headers declaring what it uses, rather than relying on the precompiled header or transitive includes. Generated with clang-tidy misc-include-cleaner, plus one hand edit making CalibrationPanel.hpp self-contained.

* Drop the OS-Specific Includes Added Outside Their Platform Guards

GLib, GTK, D-Bus and POSIX headers are only used inside platform #if blocks, which already include them. Added unconditionally at the top of the file they broke the Windows build.

* Add the clang-tidy Configuration That Generated These Includes

Only misc-include-cleaner's missing-include check, with the headers it must never suggest: per-platform, internal and OS-specific ones that would break other platforms or are not meant to be included directly.

* Match Windows Paths in the clang-tidy Ignore List

Header paths use backslashes on Windows, so every / in a pattern is now [/\\]. The Windows SDK headers are ignored alongside the other OS-specific ones, and the list is one pattern per line. Suggested by @raistlin7447 from a Windows clang-cl run.

src/slic3r/GUI/BackgroundSlicingProcess.cpp

@@ -4,8 +4,26 @@
 #include "MainFrame.hpp"
 #include "format.hpp"
 
+#include <cstddef>
+#include <exception>
+#include "libslic3r/Config.hpp"
+#include <cstdint>
+#include <functional>
 #include <libslic3r/Exception.hpp>
+#include <utility>
+#include <string>
+#include <vector>
+#include <new>
+#include "libslic3r/GCode/ThumbnailData.hpp"
+#include "libslic3r/PrintConfig.hpp"
+#include "libslic3r/Zipper.hpp"
+#include <mutex>
+#include "libslic3r/PrintBase.hpp"
+#include <ostream>
+#include <memory>
+#include "libslic3r/Polygon.hpp"
 #include <wx/app.h>
+#include <wx/event.h>
 #include <wx/panel.h>
 #include <wx/stdpaths.h>
 
@@ -36,6 +54,7 @@
 #include "I18N.hpp"
 // #include "RemovableDriveManager.hpp"
 
+#include "libslic3r_version.h"
 #include "slic3r/GUI/Plater.hpp"
 
 namespace Slic3r {