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/routes/health.py

@@ -174,6 +174,34 @@ async def delete_health(dog_id: int, entry_id: int, user=Depends(get_current_use
     return None
 
 
+# ------------------------------------------------------------------
+# DELETE /api/dogs/{dog_id}/health/{id}/dokument — Datei löschen
+# ------------------------------------------------------------------
+@router.delete("/{dog_id}/health/{entry_id}/dokument")
+async def delete_dokument(dog_id: int, entry_id: int, user=Depends(get_current_user)):
+    with db() as conn:
+        _check_dog_owner(conn, dog_id, user["id"])
+        entry = conn.execute(
+            "SELECT datei_url FROM health WHERE id=? AND dog_id=?", (entry_id, dog_id)
+        ).fetchone()
+        if not entry:
+            raise HTTPException(404, "Eintrag nicht gefunden.")
+
+        datei_url = entry["datei_url"]
+        if datei_url:
+            # datei_url z.B. "/media/health/health_42_abc12345.pdf"
+            filename = datei_url.lstrip("/media/")
+            path = os.path.join(MEDIA_DIR, filename)
+            if os.path.isfile(path):
+                os.remove(path)
+
+        conn.execute(
+            "UPDATE health SET datei_url=NULL, datei_typ=NULL WHERE id=?", (entry_id,)
+        )
+
+    return {"ok": True}
+
+
 # ------------------------------------------------------------------
 # POST /api/dogs/{dog_id}/health/{id}/dokument — Datei-Upload
 # ------------------------------------------------------------------