fix: agent-08 Kiosk-Härtung + 24h-Zeiteintrag-Bug

- fix: worked_minutes nutzt jetzt Sekunden statt Minuten für Overnight-Vergleich
  (end < start statt end <= start) – verhindert 24h-Anzeige bei Schnell-Stempel
  in derselben Minute (z.B. 23:34:46 → 23:34:48)
- fix: _check_arbzg() gleicher Sec-basierter Fix
- fix: KioskDeviceStatus Enum values_callable → kiosk list crasht nicht mehr
- feat: kiosk rotate-key CLI-Kommando (Status→pending, Re-Enrollment)
- feat: Kiosk-Settings in CompanyOut/CompanyUpdate Schema (require_approval,
  track_current_user, heartbeat_interval_sec)
- feat: Kiosk-Terminal-Einstellungsblock in CompanySettingsPage (🖥️)

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

backend/app/schemas/company.py

@@ -24,6 +24,9 @@ class CompanyOut(BaseModel):
     mobile_stamping_enabled: bool = True
     overtime_overdraft_allowed: bool = True
     overtime_warning_threshold_hours: int = 0
+    kiosk_require_approval: bool = True
+    kiosk_track_current_user: bool = True
+    kiosk_heartbeat_interval_sec: int = 30
 
 
 class CompanyUpdate(BaseModel):
@@ -36,6 +39,9 @@ class CompanyUpdate(BaseModel):
     mobile_stamping_enabled: bool | None = None
     overtime_overdraft_allowed: bool | None = None
     overtime_warning_threshold_hours: int | None = Field(None, ge=0)
+    kiosk_require_approval: bool | None = None
+    kiosk_track_current_user: bool | None = None
+    kiosk_heartbeat_interval_sec: int | None = Field(None, ge=10, le=120)
 
 
 class DepartmentOut(BaseModel):