chore: Move to Typescript (#2783)

This PR moves the entire project to Typescript. Due to the ~1000 ignores this will lead to a messy codebase for a while, but the churn is worth it – all of those ignore comments are places that were never type-safe previously.

closes #1282

shared/utils/date.ts

@@ -0,0 +1,21 @@
+import { subDays, subMonths, subWeeks, subYears } from "date-fns";
+import { DateFilter } from "@shared/types";
+
+export function subtractDate(date: Date, period: DateFilter) {
+  switch (period) {
+    case "day":
+      return subDays(date, 1);
+
+    case "week":
+      return subWeeks(date, 1);
+
+    case "month":
+      return subMonths(date, 1);
+
+    case "year":
+      return subYears(date, 1);
+
+    default:
+      return date;
+  }
+}