feat: enhance GCP deployment by adding base64 env handling and improving git pull command

[ronibhakta1]

This pull request updates the deployment workflow to improve environment variable management and ensure consistent, secure configuration on the production VM. The key changes focus on using base64-encoded secrets for environment files and enhancing the deployment process for reliability.

Deployment workflow improvements:

• The DOTENV_B64 and POCKET_ENV_B64 environment variables are now passed to the deploy job as base64-encoded secrets, providing a single source of truth for production configuration and avoiding manual edits on the VM. (.github/workflows/deploy.yml)
• The deployment script now decodes these secrets to regenerate the .env and pocket-tts.env files on the VM, overwriting any existing versions and ensuring up-to-date configuration. (.github/workflows/deploy.yml)
• The git pull command is updated to use --ff-only for safer, non-interactive updates. (.github/workflows/deploy.yml)
• Added set -euo pipefail for stricter error handling in the deployment script. (.github/workflows/deploy.yml)