refactor: Move recipe generator to cook/ directory and fix flattening bugs

- Move recipe-generator/ to cook/ for cleaner structure

- Fix ksflatten-relative path conversion to handle all %include paths

- Fix validation exit code to only fail on actual errors

- All recipes now generate and flatten successfully via make all

cook/ingredients/desktop/labwc/config.ks

@@ -0,0 +1,19 @@
+# Untested
+
+xconfig --startxonboot # Start the display session on boot. Although it says --startx, which seems to imply xorg, it is actually generic and thus works also with Wayland.
+
+%packages --exclude-weakdeps # Beginning of the packages section. Excludes weak package dependencies.
+
+@base-graphical
+## provides the following as mandatory packages:
+# mesa-dri-drivers
+# mesa-vulkan-drivers
+# plymouth-system-theme
+
+labwc # A Wayland window-stacking compositor
+
+## Extra hand-picked packages
+firefox # Mozilla Firefox Web browser
+mozilla-ublock-origin.noarch # An efficient blocker for Firefox
+
+%end # End of the packagages section