feat: enhance diagnostics script and documentation for Redis connection issues

docs/collect-diagnostics.sh

@@ -43,7 +43,10 @@ echo "=== 7. Redis memory ==="
 R="$(docker ps --format '{{.Names}}' | grep -i -m1 redis || true)"
 if [ -n "$R" ]; then
     docker exec "$R" redis-cli info memory 2>/dev/null | grep -E "used_memory_human|maxmemory_human|maxmemory_policy"
+    docker exec "$R" redis-cli info server 2>/dev/null | grep -E "uptime_in_seconds|uptime_in_days"
     docker exec "$R" redis-cli xlen messages 2>/dev/null && echo "(messages stream length above)"
+    echo "--- last redis logs:"
+    docker logs --tail 15 "$R" 2>&1
 fi
 
 echo ""