Update Desktop, Obsidian client color theme to lighter yellow

- Update background color to a different shade of white
- Make primary and primary hover colors less intense and more aligned
  with lantern flame shade
- Add water, leaf, flower color variables

src/interface/obsidian/styles.css

@@ -8,7 +8,7 @@ If your plugin does not need CSS, delete this file.
 */
 
 :root {
-    --khoj-chat-primary: #ffb300;
+    --khoj-chat-primary: #fee285;
     --khoj-chat-dark-grey: #475569;
  }