feat(theme): finish neon-glass polish (#88)

Rewrite whole-swap rofi.rasi to rofi-native @colors (was invalid CSS
var()); cyan glass panel matching Boreal's hex-alpha pattern. btop
titles/selection in accent cyan; ui rounding/opacity tuned; preview.png
from theme-shot. Bar stays generated from JSON (no waybar.css).

Verified: V2 — contrast 24×7; theme-wholeswap; theme-shot neon-glass
desktop+menu viewed; boreal theme-shot regression green.

themes/neon-glass/btop.theme

@@ -1,9 +1,10 @@
+# Neon Glass — btop whole-swap (keep hexes aligned with neon-glass.json)
 theme[main_bg]="#0B0E14"
 theme[main_fg]="#E0E6F0"
-theme[title]="#E0E6F0"
+theme[title]="#00F0FF"
 theme[hi_fg]="#00F0FF"
 theme[selected_bg]="#1E2530"
-theme[selected_fg]="#E0E6F0"
+theme[selected_fg]="#00F0FF"
 theme[inactive_fg]="#4B566B"
 theme[graph_text]="#8F9BB3"
 theme[meter_bg]="#151A22"