feat: clean up filters

Some sorely needed reorganization and pruning

config/filters/collection.js

@@ -0,0 +1,28 @@
+import date from "./date.js";
+
+const filterFavourites = (collection) => {
+  return collection.filter(
+    (item) => item.data.favourite || item.data.isFavourite,
+  );
+};
+
+const organizeByYear = (collection) => {
+  const collectionByYear = {};
+
+  collection.forEach((item) => {
+    const year = date.formatDate(item.date, "YYYY");
+
+    if (!collectionByYear[year]) {
+      return (collectionByYear[year] = [item]);
+    }
+
+    collectionByYear[year].push(item);
+  });
+
+  return collectionByYear;
+};
+
+export default {
+  filterFavourites,
+  organizeByYear,
+};