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/edward

@@ -0,0 +1,10 @@
+language variant
+name Edward
+klatt 5
+voicing 100
+consonants 70 80
+
+formant 1 92 100 130
+formant 2 103 100 80
+formant 3 103 100 70
+formant 4 114 100 60