[BUG] Fix unnecessary double conversion in Windows getSymbol

[tazarov]

Description

The Windows implementation of getSymbol in ort/library_windows.go uses an unnecessary double conversion through unsafe.Pointer that is error-prone.

Current Code

File: ort/library_windows.go:24

func getSymbol(handle uintptr, symbol string) (uintptr, error) {
    proc, err := windows.GetProcAddress(windows.Handle(handle), symbol)
    if err != nil {
        return 0, err
    }
    return uintptr(unsafe.Pointer(proc)), nil  // Double conversion
}

Issue

The double conversion uintptr(unsafe.Pointer(proc)) is unnecessary because:

• windows.GetProcAddress returns *byte
• This can be converted directly to uintptr
• The intermediate unsafe.Pointer step adds no safety

Proposed Fix

func getSymbol(handle uintptr, symbol string) (uintptr, error) {
    proc, err := windows.GetProcAddress(windows.Handle(handle), symbol)
    if err != nil {
        return 0, err
    }
    // Direct conversion - GetProcAddress returns *byte which is uintptr-compatible
    return uintptr(proc), nil
}

Impact

• Severity: Low (current code works, but is unnecessarily complex)
• Priority: Medium (should fix before v1.0)
• Risk: Minimal (simplification of existing working code)

Testing

• Verify Windows builds still compile
• Run existing tests on Windows platform
• No behavior change expected

Related

• Identified in PR [ENH] Implement ONNX Runtime environment management #15 review
• Part of code quality improvements before v1.0

Acceptance Criteria

• Remove unnecessary unsafe.Pointer intermediate conversion
• Add comment explaining why direct conversion is safe
• Verify Windows tests pass
• Consider adding Windows-specific test if none exist