Implemented phase 6 for the POC prototype in the Website service.

Services/Website/Sources/Library/Internal/Extensions/Date+Stamps.swift

@@ -18,6 +18,29 @@ extension Date {
         }
     }
 
+    /// The days an event runs over, e.g. `Sat 26 – Sun 27 Sep`.
+    static func span(
+        from start: Date,
+        to end: Date
+    ) -> String {
+        let first = start.formatted(style.weekday(.abbreviated).day())
+        let last = end.formatted(style.weekday(.abbreviated).day().month(.abbreviated))
+
+        return calendar.isDate(start, inSameDayAs: end) ? last : "\(first) – \(last)"
+    }
+
+    /// Whether the date falls within the week from the given moment: an event "this weekend".
+    func isWithinAWeek(
+        of now: Date
+    ) -> Bool {
+        (0..<7 * 86_400).contains(timeIntervalSince(now)) || Self.calendar.isDate(self, inSameDayAs: now)
+    }
+
+    /// The date as a day on a record, e.g. `20 Sep`.
+    var dayStamp: String {
+        formatted(Self.style.day().month(.abbreviated))
+    }
+
     /// The date as a stamp on a record: `today, 09:14`, `yesterday, 21:38`, `20 Sep, 14:05`, or with the year once it differs.
     ///
     /// Read on Amsterdam's clock: the marketplace is NL-first.