fix(render): strip image preload links with imagesrcset or imagesizes when as=image is omitted

[Tyagiquamar]

Closes #3753.

React 19 can emit image preload hints that carry imagesrcset/imagesizes without an as=image attribute. stripImagePreloadLinks only removed preloads with as=image, so these tags survived into the rendered email HTML even though email clients ignore link rel=preload.

This widens isImagePreloadLink to also strip preload links carrying imagesrcset or imagesizes attributes. Non-image preloads (as=style, as=font) and other link tags are still kept, covered by the existing tests.

Verification: added a regression test (fails before the fix, passes after); full @react-email/render suite passes (9/9 in the touched spec; the only full-suite failure observed was a flaky pretty.spec.ts timeout that passes in isolation).

Note: this supersedes #3743, which was closed for targeting main, missing an issue, and containing an unrelated commit. This submission follows the requested flow: issue #3753 first, clean branch from current upstream canary containing only this fix.

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Summary by cubic

Strips image preload links that carry imagesrcset or imagesizes even when as="image" is omitted, so React 19 responsive-image hints no longer leak into rendered email HTML. Closes #3753. Non-image preloads like as="style" and as="font" are still kept.

^{Written for commit 17e3d5f. Summary will update on new commits.}

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🦋 Changeset detected

Latest commit: 17e3d5f

The changes in this PR will be included in the next version bump.

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@react-email/render	Patch

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[felipefreitag]

I could not reproduce the issue, so I am closing this PR. The details are in #3753.