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/m5

@@ -0,0 +1,15 @@
+language variant
+name male5
+gender male
+
+formant 0 100  85 130
+formant 1  90  85 130  40
+formant 2  80  85 130  310
+formant 3 105  85 130
+formant 4 105  85 130
+formant 5 105  85 130
+formant 6 105  85 150
+formant 7 105  85 150
+formant 8 105  85 150
+
+intonation 2