[Tauri][wip] Fix theme integration

[martpie]

do not merge. not ready. code sucks. the whole process sucks. I have to draw a flow chart from scratch.

I need to move that code to a single-direction-data-flow.

What we need to reimplement:

• Museeks 0.13 behavior, but for Tauri
  • "System" theme
    • Window theme is correctly set (already done by Tauri, when theme is None)
      • [hard] While making explicit light/dark initial window theme work
    • Update theme based on the ThemeChanged event
  • "Dark" or "Light" theme
    • Set dark/light window theme on startup
    • Set dark/light app content theme on startup
    • [hard] Update window theme at runtime when user selects a new theme

[martpie]

Remove that after testing

[martpie]

Actually already fixed