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/boris

@@ -0,0 +1,15 @@
+language variant
+name Boris
+
+formant 0 47 120 100
+formant 1 100 90 75
+formant 2 104 100 75
+formant 3 57 80 75
+formant 4 104 80 75
+formant 5 107 80 75
+formant 6 68 0 75
+formant 7 105 0 75
+formant 8 105 0 75
+
+
+