Replace native <select> language picker with styled dropdown

The native <select> looked like a form control ("cheap"). Replace it with
the same HTML+CSS pattern as the React LanguagePicker: btn-inline-link
toggle with a translate icon, Bootstrap dropdown-menu for the list, active
item highlighted in green.

A tiny self-contained inline script handles the toggle since Bootstrap JS
is not loaded on React-layout pages. It builds the return_to URL from
window.location.pathname at click time (same as the old select approach).

Added top: auto / bottom: 100% to .language-picker .dropdown-menu so the
list always opens upward regardless of whether Popper.js is present.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

services/web/app/views/layout/language-picker.pug

@@ -1,10 +1,54 @@
 li.language-picker
-	select.language-picker-select(
-		name='lng'
-		translate='no'
-		onchange='window.location.href="/set-language?lng="+encodeURIComponent(this.value)+"&return_to="+encodeURIComponent(window.location.pathname)'
-		aria-label=translate('select_a_language')
-	)
-		each lngCode in availableLanguages
-			if settings.translatedLanguages[lngCode]
-				option(value=lngCode selected=lngCode === currentLngCode)= settings.translatedLanguages[lngCode]
+	.dropdown
+		button#language-picker-toggle.btn-inline-link(
+			type='button'
+			aria-haspopup='true'
+			aria-expanded='false'
+			aria-label=translate('select_a_language')
+			translate='no'
+		)
+			span.material-symbols translate
+			|  
+			span.language-picker-text= settings.translatedLanguages[currentLngCode] || currentLngCode
+		ul.dropdown-menu.dropdown-menu-sm-width(
+			role='menu'
+			aria-labelledby='language-picker-toggle'
+			translate='no'
+		)
+			each lngCode in availableLanguages
+				if settings.translatedLanguages[lngCode]
+					li(role='none')
+						a.dropdown-item(
+							role='menuitem'
+							data-lng=lngCode
+							class=lngCode === currentLngCode ? 'active' : ''
+						)= settings.translatedLanguages[lngCode]
+	script.
+		(function () {
+			var toggle = document.getElementById('language-picker-toggle')
+			var menu = toggle && toggle.parentElement.querySelector('.dropdown-menu')
+			if (!toggle || !menu) return
+			// Build return_to at runtime so the href reflects the actual current path
+			menu.querySelectorAll('a[data-lng]').forEach(function (a) {
+				var lng = a.getAttribute('data-lng')
+				a.href =
+					'/set-language?lng=' +
+					encodeURIComponent(lng) +
+					'&return_to=' +
+					encodeURIComponent(window.location.pathname)
+			})
+			function close() {
+				menu.classList.remove('show')
+				toggle.setAttribute('aria-expanded', 'false')
+			}
+			toggle.addEventListener('click', function (e) {
+				e.stopPropagation()
+				var opening = !menu.classList.contains('show')
+				menu.classList.toggle('show', opening)
+				toggle.setAttribute('aria-expanded', String(opening))
+			})
+			document.addEventListener('click', close)
+			document.addEventListener('keydown', function (e) {
+				if (e.key === 'Escape') { close(); toggle.focus() }
+			})
+		})()

services/web/frontend/stylesheets/components/footer.scss

@@ -218,6 +218,11 @@ footer.site-footer {
 }
 
 .language-picker .dropdown-menu {
+  // Open upward — Popper.js isn't available on all page layouts
+  top: auto;
+  bottom: 100%;
+  margin-bottom: var(--spacing-02);
+
   .dropdown-item {
     &.active {
       color: var(--green-70);