Add contact person into Teams notification post

### Feature Description

Add a new input parameter to the shared workflow that accepts a GitHub username of a responsible contact person. This username will be included in Teams notification posts to draw the attention of the right person from the team.

### Problem / Opportunity

Teams notifications currently lack a direct mention of the responsible person, leading to delayed response and unclear ownership. Adding a contact person parameter improves accountability and response time.

### Acceptance Criteria

1. A new optional input parameter (e.g. contact_person) accepting a GitHub username is added to the shared workflow.
2. The Teams notification post renders the GitHub username visibly (e.g. @username).
3. Parameter is optional — notification still works without it.

### Proposed Solution

Extend the shared workflow inputs with a contact_person string parameter. Pass it to the Teams notification step and include it in the message body/card.

### Dependencies / Related

_No response_

### Additional Context

_No response_