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/Cargo.toml

@@ -32,6 +32,7 @@ windows = { version = "0.58", features = [
     "Win32_System_ProcessStatus",
     "Win32_System_Memory",
     "Win32_System_LibraryLoader",
+    "Win32_System_Kernel",
     "Win32_Security",
     "Win32_UI_WindowsAndMessaging",
 ] }