feat: implement user profile management with avatars, login, and personal data

- Add avatar upload functionality with public URL access.
- Implement user login with email and password authentication.
- Create endpoints for fetching and updating the authenticated user's profile.
- Set up database migrations for user profiles, including email and role management.
- Introduce personal data management linked to user profiles.
- Add email verification process with welcome email templates.

auth/roles.go

@@ -0,0 +1,43 @@
+package auth
+
+type role string
+
+const (
+	roleUser  role = "user"
+	roleAdmin role = "admin"
+)
+
+func (r role) String() string {
+	return string(r)
+}
+
+func (r role) IsValid() bool {
+	return r == roleUser || r == roleAdmin
+}
+
+func (r role) IsAdmin() bool {
+	return r == roleAdmin
+}
+
+func (r role) IsUser() bool {
+	return r == roleUser
+}
+
+// RoleOption describes a valid role for display in admin UIs.
+type RoleOption struct {
+	Name  string `json:"name"`
+	Value string `json:"value"`
+}
+
+// Roles returns every valid role with a display name and its underlying value.
+func Roles() []RoleOption {
+	return []RoleOption{
+		{Name: "User", Value: string(roleUser)},
+		{Name: "Admin", Value: string(roleAdmin)},
+	}
+}
+
+// IsValidRole reports whether value is a valid role.
+func IsValidRole(value string) bool {
+	return role(value).IsValid()
+}