Use pinned snapshot for all Qt container packages

ober

cc49a8a542b7aa12b1301ad78fee077a9ef1d6ab

diff --git a/Dockerfile.qt b/Dockerfile.qt
index c1f43cc..cca343e 100644
--- a/Dockerfile.qt
+++ b/Dockerfile.qt
@@ -25,13 +25,13 @@ ARG APT_SNAPSHOT=20260701T000000Z
 ENV DEBIAN_FRONTEND=noninteractive
 ENV PATH=/root/.cargo/bin:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin
 
-RUN apt-get update && apt-get install -y --no-install-recommends ca-certificates && \
-    sed -Ei \
-      -e "s#https?://(archive|security)\\.ubuntu\\.com/ubuntu/?#https://snapshot.ubuntu.com/ubuntu/${APT_SNAPSHOT}/#g" \
-      -e "s#https?://ports\\.ubuntu\\.com/ubuntu-ports/?#https://snapshot.ubuntu.com/ubuntu/${APT_SNAPSHOT}/#g" \
+RUN sed -Ei \
+      -e "s#https?://(archive|security)\\.ubuntu\\.com/ubuntu/?#http://snapshot.ubuntu.com/ubuntu/${APT_SNAPSHOT}/#g" \
+      -e "s#https?://ports\\.ubuntu\\.com/ubuntu-ports/?#http://snapshot.ubuntu.com/ubuntu/${APT_SNAPSHOT}/#g" \
       /etc/apt/sources.list.d/ubuntu.sources && \
     apt-get update && apt-get install -y --no-install-recommends \
     bash \
+    ca-certificates \
     cmake \
     curl \
     file \