GPThemes not overriding ChatGPT theme mode after page refresh (#48)

[itsmartashub]

refactor(theme-mode-consistency): Sync GPT theme mode with GPThemes (#48)

• Rewrite the theme manager to directly mutate the value of GPT theme in local storage, eliminating the need for storage.sync
• Ensure that theme changes from GPT settings are now reflected in the floating theme and are in sync
• Note: There is a small issue with dark and accent themes on the /share/* page due to overriding code

Changes summary:

• Improved the theme management system:
  • Replaced the use of storage.sync with direct mutation of the GPT theme value in local storage, enhancing performance and reliability.
  • Ensured that theme changes from GPT settings are now properly reflected in the floating theme, maintaining a consistent user experience.
  • Identified a minor issue with dark and accent themes on the /share/* page, which will require further attention to resolve the overriding code.