Include image URL in validation error messages

[fabidick22]

Issue #, if available:

Description of changes:
Enhances error logging in the image validation process by including the source URL in error messages when image format validation fails. This significantly improves debugging experience by providing immediate context about which image caused the failure.

Motivation:
Previously, when an image validation error occurred, the error logs did not include the URL of the problematic image, so you needed:

1. Find the error log with the requestId
2. Search through multiple log entries to find other logs with the same requestId
3. Locate the URL from those related logs

Changes:

• Modified validateImageMagicNumbers to accept optional url parameter
• Updated all error messages within the method to include URL context
• Added and updated tests to cover this refactor

Example output:
Before:

{
  "errorType": "InvalidImage",
  "clientMessage": "Content-Type image/png does not match detected format jpeg"
}

After:

{
  "errorType": "InvalidImage",
  "clientMessage": "Content-Type image/png does not match detected format jpeg from: https://example.com/image.png"
}

Checklist

• 👋 I have added unit tests for all code changes.
• 👋 I have run the unit tests, and all unit tests have passed.
• ⚠️ This pull request might incur a breaking change.

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