Bugfix env setup and leverage latest features

[bradleyramos]

This PR is designed to improve current bugs in the environment setup and leverage newly available features and strategies to create the best possible result.

• Updated model names to latest versions
• Fixed bugs introduced during the deployment of dependent services (BigQuery, GCS)
• Improved prompts to specify that each scene should remain in one environment, playing to Veo's strengths
• Enforced aspect ratio for image generation outputs to maintain consistency using the updated google-genai library

[happyhuman]

Please run pylint on all the python files in this PR before submitting it for review.

[bradleyramos]

@happyhuman I have resolved all pylint alerts on the repository, thank you for the feedback!

[happyhuman]

A new script was just added to the repo: ROOT/python/python-checks.sh

Please update your branch, and use this script to catch any lint issues. You can use it to check any formatting issues:

cd python
./python-checks.sh --run-lint agents/product-catalog-ad-generation
./python-checks.sh --run-black agents/product-catalog-ad-generation
./python-checks.sh --run-isort agents/product-catalog-ad-generation

The lint issues need to be addressed and corrected. For black and isort, you may automatically fix them by running:

pip install black isort flake8   # In case the have not been already installed.
black agents/product-catalog-ad-generation
isort agents/product-catalog-ad-generation

Please address these, as well as any remaining comments which have not been resolved. We can then go ahead and have this PR approved.

[bradleyramos]

@happyhuman Thanks for your patience and for the linting hints, the automated fixes were super helpful! I've incorporated your feedback and validated the linting requirements. Please let me know if you have any other concerns.