Show soundtrack covers and edit alternative names (#49)

Covers: statistics cards show the soundtrack's cover on the left, and the
statistics popup shows it large. Until it arrives, and without a cover, the
soundtrack's initials stand in. Covers load only for cards on or near the
screen, three at a time, and are cached in covers/ next to the settings
(CoverCache), downloaded again only when cover_modified changes. The index and
file handling are shared with CharacterCache in a new FileCache.

Alternative names: the popup shows them and has an editor (add, remove, save)
that sends PUT /soundtracks/{uuid}/alternative-names. The statistics search and
the Search popup find soundtracks by them; Search shows the matching name after
the real one. Search now loads /soundtracks, falling back to the plain list.

The API types are regenerated from the server's spec, with a SoundtrackCover
theme style in every theme.

Closes #49

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

popups/search_popup.gd

@@ -1,7 +1,8 @@
 class_name SearchPopup
 extends BasePopup
 ## Searches every soundtrack on the server as you type, with [SoundtrackSearch], and
-## highlights the letters that matched.
+## highlights the letters that matched. Soundtracks are also found by their alternative
+## names; the alternative name that matched is shown after the real name.
 
 ## Every soundtrack on the server, sorted by name.
 var soundtracks: Array = []
@@ -10,6 +11,8 @@ var _matcher: SoundtrackSearch = SoundtrackSearch.new()
 # One row per soundtrack, in the order of soundtracks. Rows are reused between searches.
 var _rows: Array[PanelContainer] = []
 var _index_of: Dictionary = {}
+# The other names of each soundtrack, by its real name
+var _alternatives: Dictionary = {}
 
 @onready var search_panel: Panel = %SearchPanel
 @onready var search_field: LineEdit = %SearchField
@@ -86,19 +89,25 @@ func get_list_of_soundtracks() -> void:
 	if Settings.is_offline():
 		set_soundtracks(Settings.music_folder.soundtrack_names())
 		return
-	var handle_soundtracks: Callable = func handle_soundtracks(array: Variant) -> void:
-		if typeof(array) == TYPE_ARRAY:
-			set_soundtracks(array)
-		else:
-			GameLog.warning("Unexpected data")
-	MusicServerClient.fetch_all_soundtracks_ordered(handle_soundtracks)
+	var with_names: Callable = func with_names(list: Array[Soundtrack]) -> void:
+		var names: Array[String] = []
+		var alternatives: Dictionary = {}
+		for soundtrack: Soundtrack in list:
+			names.append(soundtrack.name)
+			alternatives[soundtrack.name] = soundtrack.alternative_names
+		names.sort_custom(func(a: String, b: String) -> bool:
+			return a.naturalnocasecmp_to(b) < 0)
+		set_soundtracks(names, alternatives)
+	MusicServerClient.fetch_soundtracks(with_names, _load_names_only)
 
 
 ## Replaces the searchable soundtracks and shows them, keeping the current search.
-func set_soundtracks(list: Array) -> void:
+## [param alternatives] has the other names of a soundtrack, by its real name.
+func set_soundtracks(list: Array, alternatives: Dictionary = {}) -> void:
 	soundtracks = []
 	soundtracks.append_array(list)
-	_matcher.set_names(soundtracks)
+	_alternatives = alternatives
+	_matcher.set_names(soundtracks, alternatives)
 	_index_of.clear()
 	for index: int in range(soundtracks.size() - 1, -1, -1):
 		_index_of[soundtracks[index]] = index
@@ -145,9 +154,25 @@ func _make_row() -> PanelContainer:
 	return row
 
 
+# Servers without /soundtracks only list the names
+func _load_names_only() -> void:
+	MusicServerClient.fetch_all_soundtracks_ordered(func(array: Variant) -> void:
+		if typeof(array) == TYPE_ARRAY:
+			set_soundtracks(array)
+		else:
+			GameLog.warning("Unexpected data"))
+
+
 func _show_name(row: PanelContainer, soundtrack_name: String, search_text: String) -> void:
-	var text: String = highlighted_name(soundtrack_name, search_text,
-			get_theme_color(&"font_color", &"HighlightLarge"))
+	var highlight: Color = get_theme_color(&"font_color", &"HighlightLarge")
+	var text: String = highlighted_name(soundtrack_name, search_text, highlight)
+	# Found by another name: show which, dimmer, after the real name
+	var alternative: String = _matcher.matched_alternative(soundtrack_name) \
+			if !search_text.is_empty() else ""
+	if !alternative.is_empty():
+		text += "  [color=#%s]%s[/color]" % [
+				get_theme_color(&"default_color", &"SongStatsSecondary").to_html(false),
+				highlighted_name(alternative, search_text, highlight)]
 	var label: RichTextLabel = row.get_child(0)
 	# Setting the same text again would make the label lay it out again for nothing
 	if label.text != text: