feat(JUVENILE-AVATARS): Foto-Avatare pro Jungtier im Wurf-Detail

- JuvenileCard-Komponente in WurfDetailPage mit 36px-Kreis-Avatar links
- Fallback auf GerbilIcon (SVG-Silhouette) wenn kein profilePhotoUrl
- URL-basiertes Fehler-Tracking (failedUrl) statt useEffect+imgError
- wuerfe.css: Flex-Layout fuer Card+Avatar, overflow:hidden/object-fit:cover
- StammbaumPage: gleiche Lint-Verletzung (react-hooks/set-state-in-effect)
  behoben (failedUrl-Pattern, kein useEffect mehr fuer Bild-Reset)
- E2E: profilePhotoUrl auf Pippa (pup-abgabe), neuer Avatar-Test

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

gerbil-manager-web/src/pages/WurfDetailPage.tsx

@@ -1,15 +1,62 @@
-import { useCallback, useMemo } from 'react'
+import { useCallback, useMemo, useState } from 'react'
 import { Link, useParams } from 'react-router-dom'
 import { de } from '../strings/de'
 import { getLitter } from '../api/litters'
 import { getGerbil, listGerbils } from '../api/gerbils'
 import { listColorVarieties, listContacts } from '../api/lookups'
+import { API_BASE_URL } from '../api/client'
 import { condition } from '../api/gridify'
+import { type Gerbil } from '../api/types'
 import { useApi } from '../hooks/useApi'
 import { formatDate, genderLabel } from '../format/labels'
 import { isValidGenotype } from '../format/genotypeText'
 import { breed, fromDisplayString, genotypeToFarbschlag, UNKNOWN_FARBSCHLAG, type BreedingResult } from '../genetics'
 import BreedingResultView from '../components/BreedingResultView'
+import GerbilIcon from '../components/GerbilIcon'
+import './wuerfe.css'
+
+type JuvenileFields = (typeof de.pages.litters.detail.juvenileFields)
+
+function JuvenileCard({ g, farbe, receiver, tJf }: {
+  g: Gerbil
+  farbe: string | null
+  receiver: string | null
+  tJf: JuvenileFields
+}) {
+  const [failedUrl, setFailedUrl] = useState<string | null>(null)
+  const rawUrl = g.profilePhotoUrl
+    ? /^(https?:|data:|\/\/)/.test(g.profilePhotoUrl)
+      ? g.profilePhotoUrl
+      : `${API_BASE_URL}${g.profilePhotoUrl}`
+    : null
+  const photoUrl = rawUrl !== failedUrl ? rawUrl : null
+
+  return (
+    <Link to={`/rennmaeuse/${g.id}`} className="gerbil-card gerbil-card--with-photo">
+      <div className="juvenile-photo">
+        {photoUrl ? (
+          <img
+            src={photoUrl}
+            alt={g.name || ''}
+            className="juvenile-photo__avatar"
+            onError={() => setFailedUrl(rawUrl)}
+          />
+        ) : (
+          <GerbilIcon size="1.4rem" aria-hidden="true" />
+        )}
+      </div>
+      <div className="juvenile-body">
+        <span className="gerbil-card__name">{g.name}</span>
+        <span className="gerbil-card__meta">{genderLabel(g.gender)}</span>
+        {farbe && <span className="gerbil-card__meta">{tJf.colorVariety}: {farbe}</span>}
+        {g.goHomeDate && <span className="gerbil-card__meta">{tJf.goHomeDate}: {formatDate(g.goHomeDate)}</span>}
+        {receiver && <span className="gerbil-card__meta">{tJf.receiver}: {receiver}</span>}
+        {g.dateOfDeath && <span className="gerbil-card__meta">{tJf.dateOfDeath}: {formatDate(g.dateOfDeath)}</span>}
+        {g.causeOfDeath && <span className="gerbil-card__meta">{tJf.causeOfDeath}: {g.causeOfDeath}</span>}
+      </div>
+    </Link>
+  )
+}
 
 export default function WurfDetailPage() {
   const t = de.pages.litters
@@ -158,19 +205,11 @@ export default function WurfDetailPage() {
         <ul className="card-list">
           {(juveniles.data?.items ?? []).map((g) => {
             const farbe = farbschlagOf(g)
-            const receiver = g.receiverContactId ? contactNameById.get(g.receiverContactId) : null
+            const receiver = g.receiverContactId ? contactNameById.get(g.receiverContactId) ?? null : null
             const tJf = t.detail.juvenileFields
             return (
               <li key={g.id}>
-                <Link to={`/rennmaeuse/${g.id}`} className="gerbil-card">
-                  <span className="gerbil-card__name">{g.name}</span>
-                  <span className="gerbil-card__meta">{genderLabel(g.gender)}</span>
-                  {farbe && <span className="gerbil-card__meta">{tJf.colorVariety}: {farbe}</span>}
-                  {g.goHomeDate && <span className="gerbil-card__meta">{tJf.goHomeDate}: {formatDate(g.goHomeDate)}</span>}
-                  {receiver && <span className="gerbil-card__meta">{tJf.receiver}: {receiver}</span>}
-                  {g.dateOfDeath && <span className="gerbil-card__meta">{tJf.dateOfDeath}: {formatDate(g.dateOfDeath)}</span>}
-                  {g.causeOfDeath && <span className="gerbil-card__meta">{tJf.causeOfDeath}: {g.causeOfDeath}</span>}
-                </Link>
+                <JuvenileCard g={g} farbe={farbe} receiver={receiver} tJf={tJf} />
               </li>
             )
           })}