## What changed
- Add an x64 and ARM64 MSVC runtime preparer that uses `dumpbin` to validate
PE32+ DLL metadata, selects the declared GStreamer plugins and dependency
closure, and copies them unchanged into a private `bin/` directory.
- Reject malformed or unsupported PE metadata, path-bearing imports, delayed
imports, managed DLLs, forwarded exports, undeclared dependencies, and
case-insensitive DLL identity conflicts.
- Keep `third_party/voice/sources.json` line endings stable across Windows
checkouts so native build receipts remain valid.
## Testing
Add native Windows tests for relocated DLL loading with a restricted search
path, receipt and digest failures, duplicate identities, malformed PE headers,
unsupported loader features, and cleanup after failed preparation.
GitOrigin-RevId: 5375f21fc54f5d597f3d4e5f8fbca3df307fa2a8
