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>

common/soundtrack_search.gd

@@ -5,23 +5,36 @@ extends RefCounted
 ## letters also find the letters in order with others in between.
 ##
 ## Used by the Search popup and the statistics view, so both find the same soundtracks.
+##
+## A soundtrack is also found by its alternative names, e.g. "FF7" for "Final Fantasy
+## VII". The results are always the real names; [method matched_alternative] tells which
+## alternative name matched.
 
-## Each name as a Dictionary with its original, lowercase and cleaned form.
+## Each searchable name as a Dictionary: the soundtrack's real name ("original"), the name
+## searched in ("text"), and its lowercase and cleaned forms.
 var _names: Array[Dictionary] = []
+# The alternative name that matched in the last search, by real name
+var _matched_alternatives: Dictionary = {}
 
 ## Compiled patterns for the letters-in-order search, by cleaned search term.
 var _regex_cache: Dictionary = {}
 
 
-## Replaces the names to search in.
-func set_names(names: Array) -> void:
+## Replaces the names to search in. [param alternatives] has the other names of a
+## soundtrack, by its real name.
+func set_names(names: Array, alternatives: Dictionary = {}) -> void:
 	_names.clear()
+	_matched_alternatives.clear()
 	for soundtrack: String in names:
-		_names.append({
-			"original": soundtrack,
-			"lowercase": soundtrack.to_lower(),
-			"cleaned": clean_term(soundtrack),
-		})
+		_add_name(soundtrack, soundtrack)
+		for alternative: String in alternatives.get(soundtrack, []):
+			_add_name(soundtrack, alternative)
+
+
+## The alternative name of [param soundtrack_name] that matched in the last
+## [method find_matches], or an empty String when its real name matched.
+func matched_alternative(soundtrack_name: String) -> String:
+	return _matched_alternatives.get(soundtrack_name, "")
 
 
 ## Returns the names matching [param search_text], best matches first: plain
@@ -41,11 +54,14 @@ func find_matches(search_text: String) -> Array[String]:
 				func(entry: Dictionary) -> bool: return regex.search(entry.cleaned) != null)
 
 	var matches: Array[String] = []
+	_matched_alternatives.clear()
 	for matches_pass: Callable in passes:
 		for entry: Dictionary in _names:
 			if !seen.has(entry.original) && matches_pass.call(entry):
 				seen[entry.original] = true
 				matches.append(entry.original)
+				if entry.text != entry.original:
+					_matched_alternatives[entry.original] = entry.text
 	return matches
 
 
@@ -107,6 +123,15 @@ static func clean_term(term: String) -> String:
 			.replace("'n", "and").to_lower()
 
 
+func _add_name(soundtrack: String, text: String) -> void:
+	_names.append({
+		"original": soundtrack,
+		"text": text,
+		"lowercase": text.to_lower(),
+		"cleaned": clean_term(text),
+	})
+
+
 # Compiles the letters-in-order pattern for [param search_term], once per term
 func _compile_regex_cached(search_term: String) -> RegEx:
 	if not search_term in _regex_cache: