[Feature]: Base image mcr.microsoft.com/azure-powershell:ubuntu-24.04 ships vulnerable .NET runtime (CVE-2026-42899)

### Description of the new feature

## Summary

The `mcr.microsoft.com/azure-powershell:ubuntu-24.04` base image bundles a .NET runtime version affected by **CVE-2026-42899** (CVSS 7.5 HIGH). A new image with .NET ≥ 9.0.16 is needed to remediate the vulnerability.

## CVE Details

| Field | Value |
|---|---|
| CVE ID | [CVE-2026-42899](https://nvd.nist.gov/vuln/detail/CVE-2026-42899) |
| Severity | **7.5 HIGH** (CVSS 3.1: AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H) |
| Weakness | CWE-835 – Loop with Unreachable Exit Condition (Infinite Loop) |
| Description | ASP.NET Core allows an unauthenticated remote attacker to deny service over a network |
| Affected versions | .NET 9.x < 9.0.16 |
| Fixed in | .NET 9.0.16 |
| Microsoft Advisory | https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-42899 |

## Affected Image

### Proposed implementation details (optional)

_No response_