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/MixedFilamentDialog.cpp

@@ -2,16 +2,36 @@
 
 #include <algorithm>
 #include <cmath>
+#include <cstddef>
+#include <cstring>
 #include <functional>
 #include <map>
 #include <set>
+#include <wx/colour.h>
+#include <wx/gdicmn.h>
+#include <wx/event.h>
+#include "slic3r/GUI/Widgets/StateColor.hpp"
+#include <vector>
+#include <string>
+#include "slic3r/GUI/GUI_Utils.hpp"
+#include <wx/dc.h>
+#include <wx/dcmemory.h>
+#include <utility>
+#include <wx/chartype.h>
+#include <tuple>
+#include <wx/arrstr.h>
 #include <wx/image.h>
+#include <wx/panel.h>
 #include <wx/sizer.h>
 #include <wx/dcclient.h>
 #include <wx/dcbuffer.h>
 #include <wx/dcgraph.h>
 #include <wx/scrolwin.h>
+#include <wx/string.h>
 #include <wx/textctrl.h>
+#include <wx/toplevel.h>
+#include <wx/window.h>
+#include <wx/tglbtn.h>
 #include <wx/wrapsizer.h>
 #include <wx/tokenzr.h>