feat(ci): add Teams notification on push to develop

[shawnchan]

Sensitive Credential Checks

• As the author of these changes, I have checked for any sensitive credentials prior to this review being requested.
• As a reviewer of these changes, I have checked for any sensitive credentials prior to approving this merge.

Motivation and Context

• In GitFlow, develop is the main integration branch where feature branches are regularly merged.
• Developers working on long-lived feature branches can easily fall out of sync with develop.
• This notification ensures the team is immediately aware when develop changes — encouraging timely rebases and reducing the likelihood of complex merge conflicts later.

Description

• Introduces a GitHub Actions workflow that sends a notification to Microsoft Teams when a push is made to the develop branch. It integrates with a Power Automate flow via a secure HTTP POST request.
• GitHub secret DEV_MERGE_TEAMS_URL configured

How Has This Been Tested?

• test locally with curl

Screenshots (if appropriate):

Checklist:

• The base branch of this PR is set to develop
• It contains only changes required by issue (does not contain other PR)
• Includes link to an issue (if apply)
• I have added tests to cover my changes.