voice audit: gender-correct Gemini voices for all dialogue speakers (398/982 were mismatched, mostly female achernar on male roles); recurring characters keep one voice course-wide; distinct voices within dialogues

Co-authored-by: Cursor <cursoragent@cursor.com>

book-3-lesson-4.module

@@ -6,23 +6,23 @@ HOME_LANG_G: en
 VOICE_DEFAULT: aoede | Clear, friendly American English narrator
 VOICE_PROMPT: gacrux | Questions and cues, read clearly
 VOICE_RESPONSE: schedar | Model answers, warm and clear
-VOICE: Ali | achernar | Male student
-VOICE: Marco | schedar | Male student
-VOICE: Don | achernar | Male speaker
+VOICE: Ali | schedar | Male student
+VOICE: Marco | achird | Male student
+VOICE: Don | umbriel | Male speaker
 VOICE: Bob | achird | Male speaker
-VOICE: Jim | achernar | Male speaker
-VOICE: Ben | achird | Male speaker
-VOICE: Ann | aoede | Female speaker
-VOICE: Ted | achernar | Male speaker
-VOICE: Tom | achird | Male speaker
+VOICE: Jim | iapetus | Male speaker
+VOICE: Ben | algieba | Male speaker
+VOICE: Ann | kore | Female speaker
+VOICE: Ted | alnilam | Male speaker
+VOICE: Tom | schedar | Male speaker
 VOICE: Jo_Ann | aoede | Female speaker
-VOICE: Jeff | achernar | Male speaker
-VOICE: Kay | aoede | Female speaker
-VOICE: Sally | aoede | Female speaker
-VOICE: Tony | achernar | Male speaker
-VOICE: Beth | aoede | Female speaker
-VOICE: Frank | achird | Male speaker
-VOICE: Mary | aoede | Female speaker
+VOICE: Jeff | orus | Male speaker
+VOICE: Kay | callirrhoe | Female speaker
+VOICE: Sally | gacrux | Female speaker
+VOICE: Tony | umbriel | Male speaker
+VOICE: Beth | leda | Female speaker
+VOICE: Frank | charon | Male speaker
+VOICE: Mary | achernar | Female speaker
 VOICE: ID | achernar | speaker (auto)
 
 $LESSON 4-1: The Sounds V and W; Here and There