snes19xx/EverCal — reverse-engineered prompt

Build me a simple Linux desktop calendar app in Flutter that feels polished and minimal, not like an old utility. I want it to look good on a Linux desktop, especially with tiling window managers like Hyprland, but it should also work nicely in normal desktop environments like GNOME and KDE.

The app should let me view my calendar clearly, add manual events inside the app, and import calendar files from places like Google Calendar or Outlook using .ics files. If possible, also support reading local vdir calendars through khal, but keep that optional so the app still works without it.

Please include light and dark themes, follow the system theme when it changes, and use a modern Material 3 style. I also want two window modes, one with no titlebar for window managers and one with a normal titlebar for desktop environments.

Look up current Flutter Linux desktop docs online if you need to.