refactor: split soundtrack chapter and drive commands

tests/unit/soundtrack-transport.test.ts

@@ -12,17 +12,19 @@ import {
 describe('soundtrack transport decisions', () => {
   it('starts at the intro only on Start and otherwise chooses the matching main phrase', () => {
     expect(resolveInitialPlayback({
+      sectionId: 'start',
+      mood: 'open',
       atStart: true,
-      bias: 'open',
       entryPhrase: 0,
-      intensity: 0,
+      generation: 0,
     })).toEqual({ kind: 'intro' });
 
     expect(resolveInitialPlayback({
+      sectionId: 'infrastructure',
+      mood: 'shadow',
       atStart: false,
-      bias: 'shadow',
       entryPhrase: 3,
-      intensity: 0.5,
+      generation: 1,
     })).toEqual({ kind: 'main', offsetSeconds: mainPhraseOffsetSeconds(3) });
 
     expect(mainPhraseOffsetSeconds(Number.NaN)).toBe(0);