feat(user): require email when admin creates a user

- Add `email` as a required field in `createUserRequest`
- Enforce email format verification and database uniqueness checks in the admin user creation handler
- Update the admin user creation frontend modal with validation and form field
- Update the corresponding backend unit tests and regenerate Swagger docs

docs/docs.go

@@ -6286,10 +6286,15 @@ const docTemplate = `{
         "user.createUserRequest": {
             "type": "object",
             "required": [
+                "email",
                 "password",
                 "username"
             ],
             "properties": {
+                "email": {
+                    "type": "string",
+                    "maxLength": 255
+                },
                 "is_active": {
                     "type": "boolean"
                 },

docs/swagger.json

@@ -6279,10 +6279,15 @@
         "user.createUserRequest": {
             "type": "object",
             "required": [
+                "email",
                 "password",
                 "username"
             ],
             "properties": {
+                "email": {
+                    "type": "string",
+                    "maxLength": 255
+                },
                 "is_active": {
                     "type": "boolean"
                 },

docs/swagger.yaml

@@ -987,6 +987,9 @@ definitions:
     type: object
   user.createUserRequest:
     properties:
+      email:
+        maxLength: 255
+        type: string
       is_active:
         type: boolean
       is_admin:
@@ -1003,6 +1006,7 @@ definitions:
         minLength: 3
         type: string
     required:
+    - email
     - password
     - username
     type: object