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/Denis

@@ -0,0 +1,19 @@
+language variant
+name Denis
+gender male 35
+pitch  80 115
+flutter 0
+roughness 0
+
+
+formant 0 100 160 160
+formant 1 95 95 95
+formant 2 100 100 100
+formant 3 90 90 90
+formant 4 40 40 40
+formant 5 80 80 80
+formant 6 10 10 10
+formant 7 10 10 10
+formant 8 10 10 10
+voicing 40
+consonants 80 80