feat(overtime): Auszahlungs-Anträge durch Mitarbeiter (opt-in pro Firma)

Mitarbeiter beantragt Überstunden-Auszahlung, HR genehmigt/lehnt ab.
Firmen-Opt-in payout_request_enabled (Default aus - nur HR-Direktbuchung).
Saldo-Abzug erst bei Genehmigung; Reject/Cancel bucht nichts.

- Migration 0042: hours_payouts.status/decided_by/decided_at/rejection_reason
  + companies.payout_request_enabled (nur Spalten, RLS unveraendert)
- Router: POST /hr/payouts/request|{id}/approve|reject|cancel; list status-Filter;
  HR-Direktbuchung bleibt (status approved)
- Frontend: PayoutRequestCard (Selbstbedienung in AbsencesPage), HR-Page
  Status-Spalte + Genehmigen/Ablehnen, CompanySettings-Toggle
- 4 pytest-Cases

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

backend/app/schemas/company.py

@@ -43,6 +43,7 @@ class CompanyOut(BaseModel):
     overtime_expiry_month: int = 3
     overtime_expiry_day: int = 31
     overtime_max_carryover_hours: int | None = None
+    payout_request_enabled: bool = False
     kiosk_require_approval: bool = True
     kiosk_track_current_user: bool = True
     kiosk_heartbeat_interval_sec: int = 30
@@ -83,6 +84,7 @@ class CompanyUpdate(BaseModel):
     overtime_expiry_month: int | None = Field(None, ge=1, le=12)
     overtime_expiry_day: int | None = Field(None, ge=1, le=31)
     overtime_max_carryover_hours: int | None = Field(None, ge=0, le=9999)
+    payout_request_enabled: bool | None = None
     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)

backend/app/schemas/hours_payout.py

@@ -12,6 +12,18 @@ class HoursPayoutCreate(BaseModel):
     note: str | None = Field(None, max_length=500)
 
 
+class HoursPayoutRequest(BaseModel):
+    """Mitarbeiter beantragt Auszahlung eigener Überstunden (kein user_id – immer self)."""
+    hours: Decimal = Field(gt=0, le=999.99, decimal_places=2)
+    period_year: int | None = Field(None, ge=2000, le=2100)
+    period_month: int | None = Field(None, ge=1, le=12)
+    note: str | None = Field(None, max_length=500)
+
+
+class HoursPayoutReject(BaseModel):
+    rejection_reason: str | None = Field(None, max_length=500)
+
+
 class HoursPayoutOut(BaseModel):
     model_config = {"from_attributes": True}
 
@@ -23,8 +35,13 @@ class HoursPayoutOut(BaseModel):
     period_year: int | None
     period_month: int | None
     note: str | None
+    status: str = "approved"
+    rejection_reason: str | None = None
     created_by: uuid.UUID
     created_by_name: str = ""    # Computed im Router
+    decided_by: uuid.UUID | None = None
+    decided_by_name: str = ""    # Computed im Router
+    decided_at: datetime | None = None
     created_at: datetime