Preserve BaseOfData when rewriting PE32 images

[zanieb]

The PE specification defines BaseOfData as a four-byte field present in PE32 but absent from PE32+. Rebuilding a PE32 executable currently drops this field, shifting subsequent headers and corrupting the image. Instead, we should preserve the existing BaseOfData bytes when serializing PE32 headers.

[Copilot]

Pull request overview

This pull request fixes PE32 image rewriting by ensuring the 4-byte BaseOfData field (present in PE32, absent in PE32+) is preserved during serialization so subsequent optional-header fields are not shifted and corrupted.

Changes:

• Preserve the original BaseOfData bytes when rewriting PE32 optional headers.
• Add a regression test that rebuilds a PE32 image and asserts byte-size stability and parse/equality round-trips.

Reviewed changes

Copilot reviewed 2 out of 3 changed files in this pull request and generated no comments.

File	Description
tests/tests.rs	Adds a PE32-specific rebuild test using a 32-bit fixture to prevent header-shift regressions.
src/image.rs	Copies the on-disk BaseOfData bytes into the rebuilt header for PE32 images before serializing the rest of the optional header.

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