Add tag to header nav (#248)

This would be a way for us to highlight that "Record vaccinations" is a
new section.

![Screenshot 2025-03-10 at 11 56
23](https://github.com/user-attachments/assets/d6a71778-6ace-42b1-8511-9c76035ee953)

Author: frankieroberto

app/assets/sass/components/_tag.scss

@@ -0,0 +1,8 @@
+
+// This is like the nhsuk-tag--blue variant,
+// but without the darker border.
+.app-tag--header {
+  background-color: tint($color_nhsuk-blue, 80%);
+  border-color: tint($color_nhsuk-blue, 80%);
+  color: shade($color_nhsuk-blue, 30%);
+}

app/assets/sass/main.scss

@@ -29,6 +29,7 @@ $govuk-brand-colour: $nhsuk-link-color;
 @import 'components/button';
 @import 'components/filters';
 @import 'components/link';
+@import 'components/tag';
 
 
 @import '../../components/pagination/_pagination';

app/views/includes/header-logged-in-organisation.html

@@ -16,7 +16,7 @@
         },
         {
           url  : "/vaccinate",
-          label : "Record vaccinations",
+          label : ("Record vaccinations <span class=\"nhsuk-tag app-tag--header nhsuk-u-margin-left-2\">New</span>") | safe,
           classes: ("app-header__navigation-item--current" if currentSection == "vaccinate")
         },
         {