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/m4

@@ -0,0 +1,17 @@
+language variant
+name male4
+gender male
+
+pitch 70 110
+
+formant 0 103 100 100
+formant 1 103 100 100
+formant 2 103 100 100
+formant 3 103 100 100
+formant 4 106 100 100
+formant 5 106 100 100
+formant 6 106 100 100
+formant 7 103 100 100
+formant 8 103 100 100
+
+stressAdd -10 -10 -30 -30 0 0 60 90