fix: strip CRLF from inputs + add .gitattributes (eol=lf) -- fixes ssh username 'invalid characters'

build-and-push/action.yaml

@@ -72,6 +72,13 @@ runs:
         BUILDER_HOST: ${{ inputs.docker_host }}
         BUILDER_USER: ${{ inputs.docker_user }}
       run: |
+        # Defensive: strip any stray CR (CRLF checkout via core.autocrlf can
+        # turn "root" into "root\r", which ssh rejects with
+        # "remote username contains invalid characters").
+        SSH_KEY=$(printf '%s' "${SSH_KEY}" | tr -d '\r')
+        BUILDER_HOST=$(printf '%s' "${BUILDER_HOST}" | tr -d '\r')
+        BUILDER_USER=$(printf '%s' "${BUILDER_USER}" | tr -d '\r')
+
         mkdir -p ~/.ssh
         echo "${SSH_KEY}" > ~/.ssh/id_ed25519
         chmod 600 ~/.ssh/id_ed25519
@@ -161,7 +168,8 @@ runs:
       run: |
         ARGS=""
         while IFS= read -r line; do
-          trimmed=$(echo "${line}" | xargs)
+          # strip stray CR (CRLF checkout) and surrounding whitespace
+          trimmed=$(printf '%s' "${line}" | tr -d '\r' | xargs)
           if [ -n "${trimmed}" ]; then
             ARGS="${ARGS} --build-arg ${trimmed}"
           fi