feat(lyrics): support multiple vocalists and aligned lyrics

android/app/src/main/kotlin/com/zarz/spotiflac/NativeFinalizationPolicy.kt

@@ -43,6 +43,7 @@ internal object NativeFinalizationPolicy {
     private val lyricsInlineTimestampPattern = Regex(
         "<\\d{1,3}:\\d{1,2}(?:[.:]\\d{1,3})?>",
     )
+    private val lyricsVoicePrefixPattern = Regex("^v[1-9][0-9]*:", RegexOption.IGNORE_CASE)
 
     fun hasUsableLyricsContent(raw: String?): Boolean {
         val lyrics = raw.orEmpty().trim()
@@ -63,12 +64,7 @@ internal object NativeFinalizationPolicy {
                 cleaned = lyricsTimestampPattern.replaceFirst(cleaned, "").trim()
             }
             cleaned = lyricsInlineTimestampPattern.replace(cleaned, "").trim()
-            if (
-                cleaned.startsWith("v1:", ignoreCase = true) ||
-                cleaned.startsWith("v2:", ignoreCase = true)
-            ) {
-                cleaned = cleaned.drop(3).trim()
-            }
+            cleaned = lyricsVoicePrefixPattern.replaceFirst(cleaned, "").trim()
             if (cleaned.isNotEmpty()) return true
         }
         return false

android/app/src/test/resources/lyrics_usability_cases.tsv

@@ -1,4 +1,4 @@
-# Shared Dart/Go/Kotlin lyric-usability cases.
+# Shared Dart/Rust/Kotlin lyric-usability cases.
 # Columns: name<TAB>expected boolean<TAB>lyrics. Decode literal \n, \r, \t in lyrics.
 empty	false	
 whitespace	false	 \t\r\n 
@@ -8,6 +8,8 @@ instrumental	true	 [Instrumental:TRUE]
 timestamps_only	false	[00:01.00]\n<00:01.10>
 multiple_timestamps	false	[00:01.00][01:02:500] 
 speaker_only	false	v1:\n V2: 
+multiple_singers_only	false	[00:01.00]v3:\n[00:02.00]<00:02.00>V12:
+third_singer_text	true	[00:01.00]v3:Third singer
 inline_before_spaced_speaker	false	[00:00.00]<00:00.01> v1:
 inline_before_tabbed_speaker	false	[00:00.00]<00:00.01>\tV2:\t
 multiple_inline_speaker	false	[00:00.00]<00:00.01> <00:00.02> v2: