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/aunty

@@ -0,0 +1,19 @@
+language variant
+name Auntie
+gender female
+pitch 204 176
+flutter 12
+
+formant 0 88 85 154
+formant 1 115 80 160 -20
+formant 2 130 75 150 -200
+formant 3 123 75 150
+formant 4 125 80 150
+formant 5 125 80 150
+formant 6 110 80 150
+formant 7 110 75 150
+formant 8 110 75 150
+
+stressAdd -20 -20 -20 -20 0 0 20 120
+stressAmp 18 16 20 20 20 20 20 20
+