fix: add context to s3client, filedeploy & installer service

[aslamcodes]

Overview
This PR improves context propagation across the application, specifically updating the S3 client initialization and file deployment/installer services to accept and respect
context.Context.

Changes

• S3 Client: Updated NewS3Backend and NewS3Client to accept context.Context as an argument instead of creating a new context.Background() internally. This ensures the
  application context (and any associated timeouts/cancellations) is correctly passed to the AWS SDK loader.
• File Deploy Service: Updated DeployFile to accept context.Context and added a check for ctx.Err() to support early cancellation.
• Installer Service: Added a check for ctx.Err() in InstallScript to support early cancellation.
• Tests & Call Sites: Updated main.go, config_service.go and relevant tests to match the new function signatures.

Motivation
Ensures that the application can gracefully handle cancellations and timeouts, especially during backend initialization and file deployment operations.

Checklist

• Code compiles and runs
• Tests updated and passing