feat(ui): add Tokyo Night theme (#24054)

Co-authored-by: Gal Zahavi <38544478+galz10@users.noreply.github.com>

docs/cli/themes.md

@@ -19,6 +19,7 @@ using the `/theme` command within Gemini CLI:
   - `Holiday`
   - `Shades Of Purple`
   - `Solarized Dark`
+  - `Tokyo Night`
 - **Light themes:**
   - `ANSI Light`
   - `Ayu Light`
@@ -252,6 +253,10 @@ identify their source, for example: `shades-of-green (green-extension)`.
 
 <img src="/docs/assets/theme-solarized-dark.png" alt="Solarized Dark theme" width="600">
 
+### Tokyo Night
+
+<img src="/docs/assets/theme-tokyonight-dark.png" alt="Tokyo Night theme" width="600">
+
 ## Light themes
 
 ### ANSI Light