* 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.
The merge kept this branch's PluginConfig design, which deletes
PluginDescriptor::settings, get_plugin_settings() and ctx.params, but left
references to them behind: the slic3rutils target did not build, and the
bindings test still asserted the removed ctx.params attribute.
Port the two settings tests onto PluginConfig instead of dropping them. They
guard a field bug where a cloud-metadata refresh wiped a plugin's settings and
it silently ran on its own defaults, so the equivalent properties are still
worth pinning: that a stored config survives the refresh, and that an edited
config reaches the plugin through a real dispatch.
Also defer PluginsConfigDialog's web commands off the webview script-message
callback, as PluginsDialog already does. Its remove_preset_override handler put
a modal wxMessageBox on that stack, which is the GTK crash class fixed in
b779a7bfed/f2ccbfc8b5 for the sibling dialog.