Restructure repo so the light variant installs as theme 'tintenblau'

omarchy-theme-install clones the repo into ~/.config/omarchy/themes/<name>
and omarchy-theme-set stages only the repo root. Moving the light variant
to the root makes 'omarchy theme install' produce a working theme; the dark
variant stays as tintenblau-dark/ subfolder.

cava_theme

@@ -0,0 +1,11 @@
+[color]
+gradient = 1
+gradient_count = 8
+gradient_color_1 = '#3a5a6a'
+gradient_color_2 = '#2a3f6f'
+gradient_color_3 = '#2a3f6f'
+gradient_color_4 = '#5a4a72'
+gradient_color_5 = '#5a4a72'
+gradient_color_6 = '#3a5a6a'
+gradient_color_7 = '#5a4a72'
+gradient_color_8 = '#3a5a6a'