Color scheme based on OS settings doesn't work with default theme

[veselyn]

Describe the bug
When the default theme is selected for either of the three modes, switching to that mode doesn't apply the default theme colors since the conf file is empty by design.

To Reproduce
Steps to reproduce the behavior:

1. Run kitten themes and pick the default theme for dark mode
2. Run kitten themes and pick a light theme for light mode
3. Toggle OS modes between dark and light
4. See how the dark mode theme never gets applied

Environment details

kitty 0.38.0 (d3f93cb0cb) created by Kovid Goyal
Darwin veselins-macbook-pro 24.1.0 Darwin Kernel Version 24.1.0: Thu Oct 10 21:00:32 PDT 2024; root:xnu-11215.41.3~2/RELEASE_ARM64_T6030 arm64
ProductName:		macOS ProductVersion:		15.1.1 BuildVersion:		24B91
OpenGL: '4.1 Metal - 89.3' Detected version: 4.1
Frozen: True
Fonts:
  medium: Menlo-Regular: /System/Library/Fonts/Menlo.ttc
          Features: ()
    bold: Menlo-Bold: /System/Library/Fonts/Menlo.ttc
          Features: ()
  italic: Menlo-Italic: /System/Library/Fonts/Menlo.ttc
          Features: ()
      bi: Menlo-BoldItalic: /System/Library/Fonts/Menlo.ttc
          Features: ()
Paths:
  kitty: /Applications/kitty.app/Contents/MacOS/kitty
  base dir: /Applications/kitty.app/Contents/Resources/kitty
  extensions dir: /Applications/kitty.app/Contents/Resources/Python/lib/kitty-extensions
  system shell: /bin/zsh
System color scheme: dark. Applied color theme type: dark
Loaded config files:
  /Users/veselin/.config/kitty/kitty.conf

Config options different from defaults:
allow_remote_control       socket-only
confirm_os_window_close    0
dynamic_background_opacity True
enable_audio_bell          False
hide_window_decorations    2
listen_on                  unix:kitty-$USER
macos_option_as_alt        3
mouse_hide_wait            -1.0
shell_integration          frozenset({'no-cursor', 'no-rc'})
tab_bar_style              hidden
Added shortcuts:
	cmd+f →  select_tab
Changed shortcuts:
	cmd+k →  clear_terminal_and_scrollback
	ctrl+cmd+, →  reload_config
	opt+cmd+r →  reset_terminal
	shift+cmd+/ →  open_kitty_website

Important environment variables seen by the kitty process:
	PATH                                /Applications/kitty.app/Contents/MacOS:/opt/homebrew/bin:/opt/homebrew/sbin:/Users/veselin/.nix-profile/bin:/etc/profiles/per-user/veselin/bin:/run/current-system/sw/bin:/nix/var/nix/profiles/default/bin:/usr/local/bin:/usr/bin:/usr/sbin:/bin:/sbin
	LANG                                en_US.UTF-8
	EDITOR                              nvim
	SHELL                               /bin/zsh
	USER                                veselin
	XDG_CONFIG_DIRS                     /Users/veselin/.nix-profile/etc/xdg:/etc/profiles/per-user/veselin/etc/xdg:/run/current-system/sw/etc/xdg:/nix/var/nix/profiles/default/etc/xdg
	XDG_DATA_DIRS                       /Users/veselin/.nix-profile/share:/etc/profiles/per-user/veselin/share:/run/current-system/sw/share:/nix/var/nix/profiles/default/share
	XDG_CACHE_HOME                      /Users/veselin/.cache
	XDG_CONFIG_HOME                     /Users/veselin/.config
	XDG_DATA_HOME                       /Users/veselin/.local/share
	XDG_STATE_HOME                      /Users/veselin/.local/state