Fix Windows compilation errors

- Added Win32_System_Kernel feature for CONTEXT structure support
- Added MemoryRead error variant to GhostError enum
- Fixed all MemoryReadError -> MemoryRead { message } conversions
- Fixed all ConfigurationError -> Configuration { message } conversions
- Added missing HashMap import in pe_parser.rs
- Removed unused imports (ReadProcessMemory, HANDLE, std::mem)
- Prefixed unused variables with underscore (_file_header, _suspicious_start_patterns)

This fixes all Windows build errors on CI/CD.

ghost-core/src/yara_engine.rs

@@ -410,7 +410,7 @@ impl DynamicYaraEngine {
     /// Read memory from a specific process and region
     #[cfg(target_os = "windows")]
     fn read_process_memory(pid: u32, region: &MemoryRegion) -> Result<Vec<u8>, GhostError> {
-        use windows::Win32::Foundation::{CloseHandle, HANDLE};
+        use windows::Win32::Foundation::CloseHandle;
         use windows::Win32::System::Diagnostics::Debug::ReadProcessMemory;
         use windows::Win32::System::Threading::{OpenProcess, PROCESS_VM_READ};