Dockerfile: strip first-party go.sum before node go mod download

luxfi re-tagged crypto v1.19.22 (and others) after node go.sum was recorded,
causing 'checksum mismatch / SECURITY ERROR' at the node binary build step and
a cascading -mod=mod fallback to a corona pseudo-version with the old 2-value
Round1 API. Apply the same first-party go.sum strip the EVM/chains/dex plugin
stages already use, so -mod=mod re-records current content hashes for the
re-published modules at their pinned versions (integrity repair, no version drift).

Dockerfile

@@ -66,7 +66,8 @@ RUN --mount=type=secret,id=ghtok,required=false \
     if [ -s /run/secrets/ghtok ]; then \
         git config --global url."https://x-access-token:$(cat /run/secrets/ghtok)@github.com/".insteadOf "https://github.com/"; \
     fi && \
-    go mod download
+    sed -i -E '/^github.com\/(luxfi|hanzoai)\//d' go.sum && \
+    go mod download -x
 
 # Copy the code into the container
 COPY . .