Environment variable consistency

Ensure consistent formatting and proper usage of environment variables in Dockerfiles. Remove unnecessary quotes from ENV declarations and choose between ARG and ENV based on their intended scope - use ARG for build-time configuration that may change between builds, and ENV for runtime configuration that containers need during execution.

Key guidelines:

• Remove unnecessary quotes from ENV values unless the value contains spaces or special characters
• Use ARG for build-time parameters that configure the build process
• Use ENV when the variable needs to be available during container runtime or in RUN commands
• Maintain consistency in formatting across all environment variable declarations

Example:

# Good - consistent formatting, appropriate usage
ARG PYTHON_VERSION=3.11
ENV PIP_CACHE_DIR=/cache/pip
ENV VIRTUAL_ENV=/app/venv
ENV TRANSFORMERS_CACHE=/app/.cache/transformers

# Avoid - unnecessary quotes and inconsistent formatting  
ENV PIP_CACHE_DIR="/cache/pip"
ENV VIRTUAL_ENV=/app/venv
ENV TRANSFORMERS_CACHE="/app/.cache/transformers"

This approach improves readability, reduces confusion about when quotes are necessary, and ensures proper separation between build-time and runtime configuration.