Fix timezone display in history page (#408)

History page now respects the TZ environment variable for displaying
timestamps. Also changed from toLocaleTimeString to toLocaleString to
show both date and time for better clarity.

Changes:
- Add TIMEZONE export from env.ts using TZ environment variable
- Pass timeZone option to toLocaleString in history.tsx

src/helpers/env.ts

@@ -23,3 +23,5 @@ export const MAX_CONVERT_PROCESS =
 
 export const UNAUTHENTICATED_USER_SHARING =
   process.env.UNAUTHENTICATED_USER_SHARING?.toLowerCase() === "true" || false;
+
+export const TIMEZONE = process.env.TZ || undefined;