feat: PDB import via RawPDB, no msdia140.dll dependency

Replace DIA SDK COM-based PDB importer with RawPDB (MolecularMatters)
which reads PDB files directly via memory-mapped I/O. Adds File menu
"Import PDB..." dialog with type filtering, selection, and progress.

- Vendor raw_pdb into third_party/
- Two-phase API: enumeratePdbTypes() + importPdbSelected()
- Full recursive import of structs/unions/arrays/pointers/bitfields
- PDB import dialog with name filter, select-all, type count
- Benchmark: 1654 types from ntkrnlmp.pdb in 16ms
- Reorganize import/export files into src/imports/

third_party/raw_pdb/src/Examples/ExampleMemoryMappedFile.cpp

@@ -0,0 +1,100 @@
+// Copyright 2011-2022, Molecular Matters GmbH <office@molecular-matters.com>
+// See LICENSE.txt for licensing details (2-clause BSD License: https://opensource.org/licenses/BSD-2-Clause)
+
+#include "Examples_PCH.h"
+#include "ExampleMemoryMappedFile.h"
+
+
+MemoryMappedFile::Handle MemoryMappedFile::Open(const char* path)
+{
+#ifdef _WIN32
+	void* file = CreateFileA(path, GENERIC_READ, FILE_SHARE_READ, nullptr, OPEN_EXISTING, FILE_ATTRIBUTE_READONLY, nullptr);
+
+	if (file == INVALID_HANDLE_VALUE)
+	{
+		return Handle { INVALID_HANDLE_VALUE, INVALID_HANDLE_VALUE, nullptr, 0 };
+	}
+
+	void* fileMapping = CreateFileMappingW(file, nullptr, PAGE_READONLY, 0, 0, nullptr);
+
+	if (fileMapping == nullptr)
+	{
+		CloseHandle(file);
+
+		return Handle { INVALID_HANDLE_VALUE, INVALID_HANDLE_VALUE, nullptr, 0 };
+	}
+
+	void* baseAddress = MapViewOfFile(fileMapping, FILE_MAP_READ, 0, 0, 0);
+
+	if (baseAddress == nullptr)
+	{
+		CloseHandle(fileMapping);
+		CloseHandle(file);
+
+		return Handle { INVALID_HANDLE_VALUE, INVALID_HANDLE_VALUE, nullptr, 0 };
+	}
+
+	BY_HANDLE_FILE_INFORMATION fileInformation;
+	const bool getInformationResult = GetFileInformationByHandle(file, &fileInformation);
+	if (!getInformationResult)
+	{
+		UnmapViewOfFile(baseAddress);
+		CloseHandle(fileMapping);
+		CloseHandle(file);
+
+		return Handle { INVALID_HANDLE_VALUE, INVALID_HANDLE_VALUE, nullptr, 0 };
+	}
+
+	const size_t fileSizeHighBytes = static_cast<size_t>(fileInformation.nFileSizeHigh) << 32;
+	const size_t fileSizeLowBytes = fileInformation.nFileSizeLow;
+	const size_t fileSize = fileSizeHighBytes | fileSizeLowBytes;
+	return Handle { file, fileMapping, baseAddress, fileSize };
+#else
+	struct stat fileSb;
+
+	int file = open(path, O_RDONLY);
+
+	if (file == INVALID_HANDLE_VALUE)
+	{
+		return Handle { INVALID_HANDLE_VALUE, nullptr, 0 };
+	}
+
+	if (fstat(file, &fileSb) == -1)
+	{
+		close(file);
+
+		return Handle { INVALID_HANDLE_VALUE, nullptr, 0 };
+	}
+
+	void* baseAddress = mmap(nullptr, fileSb.st_size, PROT_READ, MAP_PRIVATE, file, 0);
+
+	if (baseAddress == MAP_FAILED)
+	{
+		close(file);
+
+		return Handle { INVALID_HANDLE_VALUE, nullptr, 0 };
+	}
+
+	return Handle { file, baseAddress, static_cast<size_t>(fileSb.st_size) };
+#endif
+}
+
+
+void MemoryMappedFile::Close(Handle& handle)
+{
+#ifdef _WIN32
+	UnmapViewOfFile(handle.baseAddress);
+	CloseHandle(handle.fileMapping);
+	CloseHandle(handle.file);
+
+	handle.file = nullptr;
+	handle.fileMapping = nullptr;
+#else
+	munmap(handle.baseAddress, handle.len);
+	close(handle.file);
+
+	handle.file = 0;
+#endif
+
+	handle.baseAddress = nullptr;
+}