Fix Gemini voice genders in books 9-12 (achernar is a female voice)

Male-described speakers were mapped to the female voice achernar (and a few
females to schedar) — 210 VOICE swaps across the four regenerated books.
Also: book-11 'Two Letters' now labeled Jane:/Ann: with female voices
instead of one Narrator (Yana's report), and junk auto-declared 'VOICE: ID'
lines dropped.

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

book-12-lesson-2.module

@@ -7,29 +7,28 @@ 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: Mark | achernar | Male student
+VOICE: Mark | achird | Male student
 VOICE: Sam | schedar | Male
-VOICE: Jack | achernar | Male
+VOICE: Jack | achird | Male
 VOICE: Mike | schedar | Male student
-VOICE: Bob | gacrux | Male
+VOICE: Bob | achird | Male
 VOICE: Sally | aoede | Female
-VOICE: Man1 | achernar | Male
+VOICE: Man1 | schedar | Male
 VOICE: Don | schedar | Male
 VOICE: Mom | gacrux | Female
 VOICE: Son | achird | Male
-VOICE: Glenn | achernar | Male
+VOICE: Glenn | achird | Male
 VOICE: Tony | schedar | Male
-VOICE: Dan | achernar | Male
+VOICE: Dan | achird | Male
 VOICE: Paula | aoede | Female
 VOICE: Clerk | aoede | Female
-VOICE: Maria | schedar | Female
-VOICE: Steven | achernar | Male
+VOICE: Maria | achernar | Female
+VOICE: Steven | schedar | Male
 VOICE: Waiter | achird | Male
 VOICE: Tommy | achird | Young male
 VOICE: Mother | aoede | Female
 VOICE: Joe | achird | Male
-VOICE: Tim | achernar | Male
-VOICE: ID | achernar | speaker (auto)
+VOICE: Tim | charon | Male
 VOICE: Narrator | achird | speaker (auto)
 
 $SESSION 2-1: Education and College Decisions