PR Checklist

Please check if your PR fulfills the following requirements:

• The commit message follows our guidelines: https://github.com/angular/angular/blob/main/contributing-docs/commit-message-guidelines.md
• Tests for the changes have been added (for bug fixes / features)
• Docs have been added / updated (for bug fixes / features)

PR Type

What kind of change does this PR introduce?

• Bugfix
• Feature
• Code style update (formatting, local variables)
• Refactoring (no functional changes, no api changes)
• Build related changes
• CI related changes
• Documentation content changes
• angular.dev application / infrastructure changes
• Other... Please describe:

What is the current behavior?

After #66068, audio[src] no longer resolves to SecurityContext.URL.

As a result, bindings using SafeResourceUrl values may no longer unwrap correctly and can render the XSS error string instead of the actual URL.

Issue Number: #66338

What is the new behavior?

Restores SecurityContext.URL handling for audio[src], matching the existing compatibility handling for img[src] and video[src].

Also adds regression coverage to verify that audio[src] resolves to SecurityContext.URL.

Does this PR introduce a breaking change?

• Yes
• No

Other information

This restores the previous behavior prior to #66068 for audio[src] bindings.