Add InfraScan workflow for auditing infrastructure

[igor-soldev]

Closes #6803

This PR adds an automated InfraScan GitHub Actions workflow to continuously audit the repository infrastructure configuration for potential security risks and cloud cost optimization opportunities.

What was added

• New GitHub Actions workflow: .github/workflows/infrascan.yml

• Workflow runs on:

  • push
  • pull_request

• Executes InfraScan using the comprehensive scanner profile

• Generates an HTML report

• Uploads the report as a GitHub Actions artifact for easier review and troubleshooting

Motivation

This change automates the Terraform and infrastructure analysis discussed in Issue #6803:

• identify potential cloud cost optimizations
• detect infrastructure security findings
• provide continuous visibility into infrastructure quality during development

InfraScan Report

Full report generated during the initial analysis:
https://infrascan.soldevelo.com/report/commcare-cloud-8c2dd527-f4b3-4a50-8de8-4c36265ae515

Environments Affected

None

Announce New Release

• (Dimagi only) After merging, I will follow these instructions to announce a new commcare-cloud release if required.