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/Lee

@@ -0,0 +1,20 @@
+language variant
+name Lee
+gender Male
+
+#echo 230 30
+pitch 85 110
+
+flutter 0
+formant 0 80 80 80 80
+formant 1 80 80 100 100
+formant 2 80 80 80
+formant 3 9 9 9
+formant 4 290 290
+formant 5 130 0 0
+formant 6 90 90 90
+formant 7 90 90 90
+formant 8 90 90 90
+stressAdd 0 0 0 200 0 0 0 100
+stressAmp 30 30 30 30 30 30 30 30 30
+