refactor: theme state

[Schwehn42]

Description

Changes the logic how setting of the theme is handled.

Before

Previously, the logic was split weirdly by using the local storage directly to set/get the theme.
Also, the Html component would hold the logic to determine what the system theme preference is.

After

Now, theme ist also part of the application store and can be set/retrieved as such with Actions etc.
The theme is is also still saved to the local storage and retrieved initially, but the local storage key name has been streamlined with the scrumlr prefix to fit with the others.

Additionally, a hook is now used to determine the theme which is set as a global attribute.

Changelog

• Add theme to the application store (as part of view), including Actions, Reducer, and Middleware.
• The middleware will now handle setting the local storage implicitly (new key: scrumlr/theme).
• Added a hook useAutoTheme which will return the currently used theme ("light" | "dark"), even if the theme is set to "auto".
• Adjust Html.tsx and ThemeSettings.tsx to use the new app state / hook.

Checklist

• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• The light- and dark-theme are both supported and tested
• The application was tested in the most commonly used browsers (e.g. Chrome, Firefox, Safari)

[github-actions]

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Deployed Images

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• ghcr.io/inovex/scrumlr.io/scrumlr-server:sha-e2d05ab

[octomind-dev]

🐙 Octomind

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commit sha: e2d05ab

[BenedictHomuth]

LGTM and works in all common browsers