Add announcement editing and reliable per-recipient mail delivery

prisma/schema.prisma

@@ -155,6 +155,7 @@ model Kita {
   dutyAssignments         DutyAssignment[]
   absences                Absence[]
   announcements           Announcement[]
+  announcementEmails      AnnouncementEmail[]
   invitations             Invitation[]
   termine                 Termin[]
   mitbringselItems        MitbringselItem[]
@@ -280,6 +281,7 @@ model User {
   alarmNotifications NotdienstAlarmNotification[]
   alarmEmails        NotdienstAlarmEmail[]
   notdienstEmails   NotdienstEmail[]
+  announcementEmails AnnouncementEmail[]
 
   @@index([kitaId])
   @@index([familyId])
@@ -697,6 +699,10 @@ model Announcement {
   title    String
   content  String
   audience AnnouncementAudience @default(ALLE)
+  revision Int @default(1)
+  editedAt DateTime?
+  updatedAt DateTime @default(now())
+  emailReady Boolean @default(true)
 
   authorId String
   author   User   @relation("AnnouncementAuthor", fields: [authorId], references: [id], onDelete: Cascade)
@@ -705,13 +711,40 @@ model Announcement {
 
   attachments Attachment[]
   reads       AnnouncementRead[]
+  emails      AnnouncementEmail[]
 
   @@index([kitaId, createdAt])
+  @@index([kitaId, updatedAt])
   @@index([authorId])
   @@unique([id, kitaId])
   @@map("announcements")
 }
 
+model AnnouncementEmail {
+  id String @id @default(cuid())
+  kitaId String
+  kita Kita @relation(fields: [kitaId], references: [id], onDelete: Cascade)
+  announcementId String
+  announcement Announcement @relation(fields: [announcementId], references: [id], onDelete: Cascade)
+  userId String
+  user User @relation(fields: [userId], references: [id], onDelete: Cascade)
+  revision Int
+  createdAt DateTime @default(now())
+  nextAttemptAt DateTime @default(now())
+  attempts Int @default(0)
+  leaseUntil DateTime?
+  claimToken String?
+  sentAt DateTime?
+  skippedAt DateTime?
+  failed Boolean @default(false)
+  lastError String?
+
+  @@unique([announcementId, revision, userId])
+  @@index([kitaId, announcementId, revision])
+  @@index([sentAt, skippedAt, nextAttemptAt])
+  @@map("announcement_emails")
+}
+
 model Attachment {
   id             String       @id @default(cuid())
   announcementId String