feat: answer received form submissions by mail

src/Config/EmailTextKey.php

@@ -12,6 +12,8 @@ enum EmailTextKey: string
 {
     case APPLICATION_ACCEPTED = 'application_accepted';
     case APPLICATION_ACCEPTED_NO_CONTRACT = 'application_accepted_no_contract';
+    case APPLICATION_FORM_FOLLOW_UP = 'application_form_follow_up';
+    case APPLICATION_FORM_RECEIVED = 'application_form_received';
     case APPLICATION_REJECTED = 'application_rejected';
     case ASSIGNMENT_CALLED_OFF = 'assignment_called_off';
     case DISPOSITION_CALLED_OFF = 'disposition_called_off';

src/Config/SeasonCalendar.php

@@ -56,6 +56,35 @@ final class SeasonCalendar
         return $day >= $start && $day <= $end ? $year : null;
     }
 
+    /**
+     * The season a mail written now would call "die kommende Saison": the one currently running,
+     * or - between two seasons - the next one to start. Never null, unlike seasonYearFor(): a
+     * recruiting mail sent in September is outside every season window but is unmistakably about
+     * the winter ahead.
+     */
+    public function currentOrUpcomingSeasonYear(\DateTimeInterface $date): int
+    {
+        if (null !== $seasonYear = $this->seasonYearFor($date)) {
+            return $seasonYear;
+        }
+
+        $day = CarbonImmutable::instance($date)->startOfDay();
+        $year = (int) $day->format('Y');
+
+        // Outside any window, so the next start is this year's unless it has already passed,
+        // which for a wrapping window can only mean the season already began - handled above.
+        return $day <= $this->boundaryFor($this->seasonStart, $year) ? $year : $year + 1;
+    }
+
+    /**
+     * 2026 -> "26/27". The short form the mails to applicants use, where "Saison 2026/27" would
+     * read like a heading in the middle of a sentence.
+     */
+    public function shortLabel(int $seasonYear): string
+    {
+        return sprintf('%02d/%02d', $seasonYear % 100, ($seasonYear + 1) % 100);
+    }
+
     /**
      * null -> "außerhalb der Saison"; 2024 -> "Saison 2024/25".
      */