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/Mario

@@ -0,0 +1,17 @@
+language variant
+name Mario
+
+pitch  75 125
+
+formant 0 100 111 95
+formant 1 100 111 60
+formant 2 95 90 55
+formant 3 100 50 65
+formant 4 69 65 65
+formant 5 79 60 75
+formant 6 89 60 75
+formant 7 99 0 100
+formant 8 109 0 100
+voicing 135
+consonants 115 120
+