[Feat]: Addition of multiple themes to the project

[Spiral-Memory]

As an EmbeddedChat developer,

I need to: Design some good-looking themes using the existing theming foundation

So that: EmbeddedChat admins have the option to choose designs that suit their website well upon integration

Acceptance Criteria

• [x] Design multiple themes

[Spiral-Memory]

Hey @sidmohanty11 , please add appropriate labels to this issue. Thanks!