fix: read one-sided booking times as "ab" and "bis"

src/Model/TimeRange.php

@@ -164,9 +164,26 @@ final readonly class TimeRange implements \Stringable
         return self::format($this->endMinute);
     }
 
+    /**
+     * One-sided spans read as "bis 13:00" / "ab 13:00" rather than 00:00–13:00 / 13:00–24:00:
+     * a half day booked by giving only one end has no meaningful other end, and midnight is not
+     * what the user typed.
+     */
     public function __toString(): string
     {
-        return $this->isAllDay() ? 'ganztägig' : $this->start().'–'.$this->end();
+        if ($this->isAllDay()) {
+            return 'ganztägig';
+        }
+
+        if (self::DAY_START === $this->startMinute) {
+            return 'bis '.$this->end();
+        }
+
+        if (self::DAY_END === $this->endMinute) {
+            return 'ab '.$this->start();
+        }
+
+        return $this->start().'–'.$this->end();
     }
 
     private static function minutesOf(\DateTimeInterface $time): int