feat: sync calendar entries to a Microsoft 365 group calendar

Adds a one-way push (ApiCore -> M365) of Aufgaben/Durchsichten/
Behandlungen/Fütterungen/Ernten/Königinnen-Zuordnungen into the calendar
of a Microsoft 365 group, via the Graph API.

- CalendarSyncModule (app-only client-credentials Graph auth, separate
  from the interactive SSO app registration; new env vars
  M365_CALENDAR_TENANT_ID/_CLIENT_ID/_CLIENT_SECRET).
- Outbox + minute-interval cron worker (CalendarSyncOutboxEntry) instead
  of a synchronous push, since Graph calls are too slow/flaky to block a
  domain create request on; failed syncs retry up to 5 times.
- Per-source-type toggle plus a group-ID field, configurable in
  Verwaltung > Automatisierung > Kalender-Sync (Verwaltung > Backup, an
  env var still wins on those fields where one applies to related config).
- Hooked into Tasks/Inspections/Treatments/Feedings/Harvests/Queens at
  their existing create (and Task update/complete) points; entries render
  as all-day Graph events to avoid timezone ambiguity.
- Documents the design decision in ARCHITECTURE.md (Annahme 9), since
  this is a net-new capability the lastenheft doesn't scope.

Co-Authored-By: Claude Sonnet 5 <[email protected]>

ApiCore-Backend/src/calendar-sync/dto/update-calendar-sync-settings.dto.ts

@@ -0,0 +1,48 @@
+import { ApiPropertyOptional } from '@nestjs/swagger';
+import { IsBoolean, IsOptional, IsString, MaxLength } from 'class-validator';
+
+export class UpdateCalendarSyncSettingsDto {
+  @ApiPropertyOptional()
+  @IsOptional()
+  @IsBoolean()
+  enabled?: boolean;
+
+  @ApiPropertyOptional({
+    description:
+      'Objekt-ID der Microsoft-365-Gruppe. Leerer String löscht den GUI-Wert.',
+  })
+  @IsOptional()
+  @IsString()
+  @MaxLength(100)
+  groupId?: string;
+
+  @ApiPropertyOptional()
+  @IsOptional()
+  @IsBoolean()
+  syncTask?: boolean;
+
+  @ApiPropertyOptional()
+  @IsOptional()
+  @IsBoolean()
+  syncInspection?: boolean;
+
+  @ApiPropertyOptional()
+  @IsOptional()
+  @IsBoolean()
+  syncTreatment?: boolean;
+
+  @ApiPropertyOptional()
+  @IsOptional()
+  @IsBoolean()
+  syncFeeding?: boolean;
+
+  @ApiPropertyOptional()
+  @IsOptional()
+  @IsBoolean()
+  syncHarvest?: boolean;
+
+  @ApiPropertyOptional()
+  @IsOptional()
+  @IsBoolean()
+  syncQueenAssignment?: boolean;
+}