Modernize Destinataer detail page: tabbed UI with integrated timeline

Replaces the old multi-card layout (1368 lines) with a compact, modern
tabbed interface (Stammdaten | Nachweise | Zahlungen | Timeline | Dokumente | Notizen).
All information is now accessible from one page without excessive clicking.

- Add timeline events to destinataer_detail view (merged from timeline view logic)
- Compact profile header with avatar initials, status badges, key contact info
- Inline editing preserved with table-based layout for cleaner data display
- Tab state persisted in URL hash for bookmarkable deep links
- Dropdown menu for less-used actions (export, archive, delete)

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

app/stiftung/views/destinataere.py

@@ -316,6 +316,52 @@ def destinataer_detail(request, pk):
     # Alle verfügbaren StiftungsKonten für das Select-Feld laden
     stiftungskonten = StiftungsKonto.objects.all().order_by("kontoname")
 
+    # Timeline events (merged from destinataer_timeline view)
+    timeline_events = []
+    for u in destinataer.unterstuetzungen.select_related("konto", "ausgezahlt_von", "freigegeben_von").order_by("-faellig_am"):
+        timeline_events.append({
+            "datum": u.faellig_am,
+            "typ": "zahlung",
+            "icon": "fa-money-bill-wave",
+            "farbe": "success" if u.status == "ausgezahlt" else ("danger" if u.is_overdue() else "primary"),
+            "titel": f"Zahlung \u20ac{u.betrag}",
+            "beschreibung": u.beschreibung or u.get_status_display(),
+            "status": u.get_status_display(),
+        })
+    for n in destinataer.quartalseinreichungen.order_by("-jahr", "-quartal"):
+        datum = n.zahlung_faelligkeitsdatum or n.faelligkeitsdatum
+        if datum:
+            timeline_events.append({
+                "datum": datum,
+                "typ": "nachweis",
+                "icon": "fa-file-alt",
+                "farbe": "success" if n.status in ("geprueft", "auto_geprueft") else ("danger" if n.is_overdue() else "warning"),
+                "titel": f"Nachweis {n.jahr} Q{n.quartal}",
+                "beschreibung": n.get_status_display(),
+                "status": n.get_status_display(),
+            })
+    for e in destinataer.email_eingaenge.order_by("-eingangsdatum"):
+        timeline_events.append({
+            "datum": e.eingangsdatum.date() if hasattr(e.eingangsdatum, "date") else e.eingangsdatum,
+            "typ": "email",
+            "icon": "fa-envelope",
+            "farbe": "info",
+            "titel": e.betreff or "(kein Betreff)",
+            "beschreibung": e.absender_email,
+            "status": e.get_status_display(),
+        })
+    for n in destinataer.notizen_eintraege.order_by("-erstellt_am"):
+        timeline_events.append({
+            "datum": n.erstellt_am.date() if hasattr(n.erstellt_am, "date") else n.erstellt_am,
+            "typ": "notiz",
+            "icon": "fa-sticky-note",
+            "farbe": "secondary",
+            "titel": n.titel or "Notiz",
+            "beschreibung": (n.text[:100] + "\u2026") if n.text and len(n.text) > 100 else n.text,
+            "status": f"von {n.erstellt_von.get_full_name() or n.erstellt_von.username}" if n.erstellt_von else "",
+        })
+    timeline_events.sort(key=lambda e: e["datum"] if e["datum"] else date.min, reverse=True)
+
     context = {
         "destinataer": destinataer,
         "verknuepfte_dokumente": verknuepfte_dokumente,
@@ -326,6 +372,7 @@ def destinataer_detail(request, pk):
         "quarterly_confirmations": quarterly_confirmations,
         "available_years": available_years,
         "current_year": current_year,
+        "timeline_events": timeline_events,
     }
     return render(request, "stiftung/destinataer_detail.html", context)