[Scorecards] Override bg-primary-* for .year-2025 pages

Also fix broken background color on main-filter-methodology component,
making it much more noticeable on the Methodology page.

scoring/static/scoring/scss/main.scss

@@ -64,3 +64,4 @@
 @import "toggle-buttons";
 @import "loading-shimmer";
 @import "open-graph-preview";
+@import "years";

scoring/static/scoring/scss/years.scss

@@ -0,0 +1,23 @@
+.year-2025 {
+    $shades: (
+        "100": $primary2025-100,
+        "200": $primary2025-200,
+        "300": $primary2025-300,
+        "400": $primary2025-400,
+        "500": $primary2025-500,
+        "600": $primary2025-600,
+        "700": $primary2025-700,
+        "800": $primary2025-800,
+        "900": $primary2025-900
+    );
+
+    .bg-primary {
+        background-color: $primary2025-500 !important;
+    }
+
+    @each $n, $shade in $shades {
+        .bg-primary-#{$n} {
+            background-color: $shade !important;
+        }
+    }
+}

scoring/templates/scoring/includes/main-filter-methodology.html

@@ -1,4 +1,4 @@
-<div class="bg-blue-l2 p-3 mb-4 border rounded">
+<div class="bg-primary-100 p-3 mb-4 border rounded">
     <label for="questions-council-name" class="d-block mb-2">Show questions for a specific council</label>
     <input class="form-control searchbar js-methodology-council-autocomplete" type="search" placeholder="Council name" aria-label="Council name" id="questions-council-name">
     <p class="mt-3 mt-lg-4 mb-2">Or show questions by type of council</p>