Agregar campo username a User entity y DTO

- Columna username (unique, nullable) en auth.users
- Campo username en CreateUserDto y UpdateUserDto

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

tts/piper/espeak-ng-data/voices/!v/Andrea

@@ -0,0 +1,20 @@
+language variant 
+name Andrea
+gender female 
+
+pitch 200 265
+roughness 0
+
+formant 0 100  100 100
+formant 1 110  100 80
+formant 2 110  80 80
+formant 3 115  110 80
+formant 4 115  80 100
+formant 5 95  50 100
+formant 6 0 0 0
+formant 7 120  100 100
+formant 8 110  100 100
+intonation 3
+stressLength 0 1 2 3 4 5 6 7
+stressAdd 130 140 140 100 0 0 130 160
+voicing 150