Create theme and styles

[NachoVazquez]

Problem Statement

We want to make LazyNx as customizable as possible, allowing users to tailor the look and feel of the application to their specific needs. This includes the ability to pick predefined themes and potentially create their own.

Proposed Solution

• Create a theme engine that styles the application based on the selected theme.
• Allow users to choose from a set of predefined themes from inside the application.
• Add a theme option to the user configuration.

Alternatives Considered

We could also have a single theme, but this is not great.

Example Usage

At any moment the user will be able to change the theme using a keybinding.

// Example of how the API might look
theme.SetTheme(params)

Additional Context

We can take inspiration from how opencode implements this feature.

https://github.com/sst/opencode/tree/dev/internal/tui/theme

Would you be willing to contribute this feature?

• Yes, I'd be willing to submit a PR for this feature
• No, I'm requesting someone else implement this feature