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/Foundation/PDB_Warnings.h

@@ -0,0 +1,45 @@
+// 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)
+
+#pragma once
+
+#include "PDB_Platform.h"
+
+#if PDB_COMPILER_MSVC
+	// some warnings were introduced with different versions of Visual Studio, so we disable this warning instead of using a bunch of #if/#endif
+#	pragma warning (disable : 4619)		// there is no warning number N
+
+	// we compile with exceptions disabled
+#	pragma warning (disable : 4530)		// C++ exception handler used, but unwind semantics are not enabled.Specify / EHsc
+#	pragma warning (disable : 4577)		// 'noexcept' used with no exception handling mode specified; termination on exception is not guaranteed. Specify /EHsc
+
+	// ignore purely informational warnings
+#	pragma warning (disable : 4514)		// unreferenced inline function has been removed
+#	pragma warning (disable : 4710)		// function not inlined
+#	pragma warning (disable : 4711)		// function selected for automatic inline expansion
+#	pragma warning (disable : 4820)		// 'N' bytes padding added after data member 'm_member'
+#	pragma warning (disable : 5045)		// Compiler will insert Spectre mitigation for memory load if /Qspectre switch specified
+#elif PDB_COMPILER_CLANG
+	// turn on absolutely all available Clang warnings
+#	pragma clang diagnostic warning "-Wall"
+#	pragma clang diagnostic warning "-Wextra"
+#	pragma clang diagnostic warning "-Weverything"
+#	pragma clang diagnostic warning "-Wpedantic"
+
+	// these warnings contradict -Weverything
+#	pragma clang diagnostic ignored "-Wc++98-compat"
+#	pragma clang diagnostic ignored "-Wc++98-compat-pedantic"
+
+	// this warning is triggered for templates which are explicitly instantiated.
+	// forgetting to instantiate the template would trigger a linker error anyway, so we disable this warning.
+#	pragma clang diagnostic ignored "-Wundefined-func-template"
+
+	// we don't strive for C++20 compatibility
+#	pragma clang diagnostic ignored "-Wc++20-compat"
+
+	// some structures will have to be padded
+#	pragma clang diagnostic ignored "-Wpadded"
+
+	// it's impossible to write C++ code using raw pointers without triggering this warning
+#	pragma clang diagnostic ignored "-Wunsafe-buffer-usage"
+#endif