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/m2

@@ -0,0 +1,15 @@
+language variant
+name male2
+gender male
+
+pitch 88 115
+echo 130 15
+formant 0 100  80 120
+formant 1  90  85 120
+formant 2 110  85 120
+formant 3 105  90 120
+formant 4 100  90 120
+formant 5 100  90 120
+formant 6 100  90 120
+formant 7 100  90 120
+formant 8 100  90 120