Force UTC for all internal date processing

src/index.ts

@@ -1,5 +1,12 @@
+// Import environment variables from .env ASAP...
+
 import "dotenv/config";
 
+// ..but globally force all date and time processing to operate in UTC.
+// Do not allow this to be overridden by .env either.
+
+process.env.TZ = "UTC";
+
 import fs from "fs";
 import https from "https";
 import http from "http";