feat(darwin-breeze): unify theme colors across KDE, Helium, T3 Code and Ghostty

Move the Darwin Breeze Dark color scheme and global theme into a stow
package. build.py generates the Helium, T3 Code and Ghostty themes from
DarwinBreezeDark.colors, and apply.sh rebuilds and applies them, so the
colors are edited in one place.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

darwin-breeze/.gitignore

@@ -0,0 +1,3 @@
+# Helium caches the built theme next to the manifest.
+Cached Theme.pak
+__pycache__/