Sprint 16: Chat-Fotos/Online/Read-Receipts, Gesundheit-Dokumente löschen, Bugfixes

- Chat: Foto-Versand (POST /api/chat/conversations/{id}/upload, media_url/media_type)
- Chat: Online-Indikator (last_seen Heartbeat, grüner Dot, 3min-Fenster)
- Chat: Read Receipts (read_at, Einzel-/Doppelhaken-Icons)
- Gesundheit: Dokument löschen (DELETE .../dokument, Datei + DB-Eintrag)
- Bug: events.user_id NOT NULL → nullable (Table-Recreation-Migration)
- Bug: scheduler INSERT user_id 0 → NULL
- Bug: Wikidata Rate-Limit: sleep 0.3s→1.0s, retries 2→4, exponentielles Backoff
- SW: by-v146, APP_VER 119

backend/scheduler.py

@@ -5,9 +5,12 @@ Täglich: Gesundheits-Erinnerungen per Push versenden.
 
 import logging
 from datetime import date, datetime, timedelta
+from zoneinfo import ZoneInfo
 from apscheduler.schedulers.asyncio import AsyncIOScheduler
 from apscheduler.triggers.cron import CronTrigger
 
+_TZ = ZoneInfo("Europe/Berlin")
+
 from database import db
 from routes.push import send_push_to_user, send_push_to_all
 import weather
@@ -64,7 +67,7 @@ def start():
     _scheduler.add_job(
         _job_import_events,
         'date',
-        run_date=datetime.now() + timedelta(seconds=10),
+        run_date=datetime.now(tz=_TZ) + timedelta(seconds=10),
         id="import_events_startup",
         replace_existing=True,
     )
@@ -72,7 +75,7 @@ def start():
     _scheduler.add_job(
         _job_prewarm_cities,
         'date',
-        run_date=datetime.now() + timedelta(seconds=90),
+        run_date=datetime.now(tz=_TZ) + timedelta(seconds=90),
         id="prewarm_cities_startup",
         replace_existing=True,
     )
@@ -80,7 +83,7 @@ def start():
     _scheduler.add_job(
         _job_seed_breeds,
         'date',
-        run_date=datetime.now() + timedelta(seconds=15),
+        run_date=datetime.now(tz=_TZ) + timedelta(seconds=15),
         id="seed_breeds_startup",
         replace_existing=True,
     )
@@ -88,7 +91,7 @@ def start():
     _scheduler.add_job(
         _job_seed_wikidata_breeds,
         'date',
-        run_date=datetime.now() + timedelta(seconds=45),
+        run_date=datetime.now(tz=_TZ) + timedelta(seconds=45),
         id="seed_wikidata_startup",
         replace_existing=True,
     )
@@ -339,7 +342,7 @@ async def _job_import_events():
                 if not exists:
                     conn.execute("""
                         INSERT INTO events (user_id, titel, datum, ort_name, typ, link, quelle, external_id, status)
-                        VALUES (0, ?, ?, ?, ?, ?, 'vdh', ?, 'aktiv')
+                        VALUES (NULL, ?, ?, ?, ?, ?, 'vdh', ?, 'aktiv')
                     """, (
                         ev['titel'],
                         ev['datum'],