* 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.
build: clear 54 dead private fields
54 of the 161 -Wunused-private-field warnings, across 31 files. These are
the ones needing no judgment. Each member is declared once and appears
nowhere else in src/, counting the .mm and .c sources as well as .cpp and
.hpp, so nothing writes them and nothing reads them. Every removal is a
whole line, and no declaration shares a line with another member.
The remaining 107 are left alone. Those members are mentioned elsewhere,
usually assigned and never read, where the fix might be deleting the
member or might be restoring a read that went missing.