feat: simplify chord guide feature; updated help doc; added hotkeys doc

src/util/scaleUtil.ts

@@ -17,6 +17,14 @@ export const getRootNoteFromKeySignature = (keySignature: KeySignature): string
   return match[1];
 };
 
+/**
+ * Resolves the chord-guide mode from a key signature.
+ * Chord guiding only supports major/minor quality and maps them to Ionian/Aeolian.
+ */
+export const getChordGuideModeFromKeySignature = (keySignature: KeySignature): 'ionian' | 'aeolian' => {
+  return keySignature.endsWith(' minor') ? 'aeolian' : 'ionian';
+};
+
 /**
  * Converts a note name (without octave) to pitch class (0-11)
  * @param noteName - Note name like "C", "C#", "Db", "F#"