docs(nativeaot): document the verified Windows-host parser route (#2497)

Squash merge of https://github.com/morluto/rea/pull/2497.

Co-authored-by: pablodiazjorge <pablodiazjorgegarcia@gmail.com>

docs/testing.md

@@ -646,6 +646,12 @@ records independent symbol/directory/SHA oracles; it never executes the target.
 Linux also builds stripped, ordinary-native and small malformed/ambiguous/layout
 negative inputs. The optional Windows fixture workflow builds a PE on a Windows
 runner; analyzing that PE on Linux does not verify a Windows Ghidra host.
+On a local Windows host, the .NET 8 ILCompiler finds the linker only through
+Visual Studio 2019 or 2022 (`vswhere -version [16,18)`). With only Visual
+Studio Build Tools 2026 installed, open its x64 Developer Command Prompt.
+In that same `cmd.exe` session, run `set IlcUseEnvironmentalTools=true` and
+then `npm run build:fixtures:nativeaot`. Running `vcvars64.bat` as a child of
+PowerShell does not preserve its environment in the parent PowerShell session.
 
 Build the clean pinned upstream adapter with `build:ghidra:nativeaot`, then set
 `REA_GHIDRA_NATIVEAOT_JAR`. Run `verify:ghidra:nativeaot -- symbols`, `-- stripped`,