Feature/ak 58 add sensitive flag OpenAI api key

[kavindu-yl]

Description

Add sensitive = true flag to the openai_api_key Terraform variable across all deployment examples to prevent the API key from being exposed in Terraform plan/apply output and state files.

Type of Change

• New feature (non-breaking change which adds functionality)

Related Issues

Relates to #58

Changes Made

• Added sensitive = true to the openai_api_key variable declaration in 19 variables.tf files across AWS, Azure, and agent deployment examples

Testing

This is a Terraform variable flag change, no functional logic was modified so no testing is required.

Checklist

• My code follows the project's style guidelines
• I have performed a self-review of my code
• My changes generate no new warnings

Additional Notes

The sensitive = true flag masks the OpenAI API key in Terraform CLI output and prevents it from being shown in plain text in state files.