Add a Christmas theme

Christmas red window and panels with snow white buttons and red text, a thick
white "fur" trim on popups, cards, the lists and the player bar, the tree's
green for the chosen tab and the play button, and gold for the playing song and
highlights. Icons on buttons take the text's colour, and drop-down lists stay
dark red so their arrow shows. It uses Nord's round shapes.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

data/settings.gd

@@ -37,6 +37,7 @@ const THEMES: Array[Dictionary] = [
 	{"id": "classic", "name": "Classic", "path": "res://themes/main_theme.tres"},
 	{"id": "original_web", "name": "Original web", "path": "res://themes/original_web_theme.tres"},
 	{"id": "nord", "name": "Nord", "path": "res://themes/nord_theme.tres"},
+	{"id": "christmas", "name": "Christmas", "path": "res://themes/christmas_theme.tres"},
 ]
 ## When this environment variable is set, the settings files are kept in that folder
 ## instead of the user's config folder. The tests set it so they never touch the real files.

tests/integration/test_theme_picker.gd

@@ -27,7 +27,7 @@ func test_picker_lists_every_theme_and_shows_the_one_in_use() -> void:
 	for index: int in _settings.theme_button.item_count:
 		names.append(_settings.theme_button.get_item_text(index))
 
-	assert_array(names).contains_exactly(["Classic", "Original web", "Nord"])
+	assert_array(names).contains_exactly(["Classic", "Original web", "Nord", "Christmas"])
 	assert_str(_settings.theme_button.get_item_text(_settings.theme_button.selected)) \
 			.is_equal("Classic")
 

themes/README.md

@@ -9,6 +9,7 @@ font sizes or style boxes themselves; they name one of the theme's styles instea
 | Classic | `main_theme.tres` | The default. Also the project theme (Project Settings → GUI → Theme → Custom), which the editor shows |
 | Original web | `original_web_theme.tres` | Looks like MusicFrontend, the web version: orange-bordered buttons, `#333` header and popups, `#424242` panels, `#4e4e4e` alternating rows, a yellow playing song and a light grey player bar |
 | Nord | `nord_theme.tres` | Dark blues from the app icon (`#1e4a69` window, `#1a3e5a` panels, `#29577f` buttons) with Nord's Snow Storm text, Frost and Aurora accents: Aurora yellow `#EBCB8B` for the playing song and highlights. Round shapes: pill buttons and tabs, 14–16 px corners, soft shadows on popups, cards and the player bar, and rounded text fields |
+| Christmas | `christmas_theme.tres` | Santa and a Christmas tree: Christmas red (`#7a1520` window, `#5c0f18` panels) with snow white buttons and red text, a thick white "fur" trim on popups, cards, the lists and the player bar, the tree's green (`#1f6b3c`) for the chosen tab and the play button, and gold for the playing song and highlights. The same round shapes as Nord |
 
 ## Picking a theme