more multi-tenancy

backend/src/utils/time.rs

@@ -0,0 +1,13 @@
+use chrono::{DateTime, NaiveDateTime, Utc};
+
+/// Format a timestamp as RFC3339 using UTC.
+pub fn to_iso(dt: NaiveDateTime) -> String {
+    DateTime::<Utc>::from_naive_utc_and_offset(dt, Utc).to_rfc3339()
+}
+
+/// Format a timestamp for HTTP headers (RFC 7231 date).
+pub fn to_http_date(dt: NaiveDateTime) -> String {
+    DateTime::<Utc>::from_naive_utc_and_offset(dt, Utc)
+        .format("%a, %d %b %Y %H:%M:%S GMT")
+        .to_string()
+}