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.

src/slic3r/GUI/WebMediaController.cpp

@@ -1,5 +1,8 @@
 #include "WebMediaController.hpp"
+#include "IPrinterAgent.hpp"
 
+#include <wx/gdicmn.h>
+#include <wx/uri.h>
 #include <wx/webview.h>
 
 namespace Slic3r { namespace GUI {