fix: prevent shell redirection issues with pip dependencies (#2867)

- Use printf to to escape special characters (e.g. < > )
- Apply escaping to pip_dependencies and special_pip_deps

Resolves shell interpretation of >= operators as redirections that were
causing build failing to respect versions and unexpected file creation
in /app directory.

Closes: #2866

## Test Plan
Manually tested, will also be tested by existing CI

Signed-off-by: Derek Higgins <derekh@redhat.com>

llama_stack/distribution/build_container.sh

@@ -136,16 +136,20 @@ EOF
 # Add pip dependencies first since llama-stack is what will change most often
 # so we can reuse layers.
 if [ -n "$pip_dependencies" ]; then
+  read -ra pip_args <<< "$pip_dependencies"
+  quoted_deps=$(printf " %q" "${pip_args[@]}")
   add_to_container << EOF
-RUN $MOUNT_CACHE uv pip install $pip_dependencies
+RUN $MOUNT_CACHE uv pip install $quoted_deps
 EOF
 fi
 
 if [ -n "$special_pip_deps" ]; then
   IFS='#' read -ra parts <<<"$special_pip_deps"
   for part in "${parts[@]}"; do
+    read -ra pip_args <<< "$part"
+    quoted_deps=$(printf " %q" "${pip_args[@]}")
     add_to_container <<EOF
-RUN $MOUNT_CACHE uv pip install $part
+RUN $MOUNT_CACHE uv pip install $quoted_deps
 EOF
   done
 fi