A solution folder is a virtual grouping, not a file: VS writes its name
as both the display name and the "path" (name == path, no real file).
extract_sln resolved it to an absolute filesystem path anyway and keyed
the node id off that. The CLI id-relativization pass only remaps ids of
real files in the scan set, so a virtual folder never matched and its
absolute id (with the local username) survived into a committed
graph.json.
Detect solution folders (name == path) and key their id/source_file off
the folder name only; real project files still resolve as before. Adds a
regression test asserting the folder node id is relative.
The earlier fix (0.9.13) covered .csproj/.sln file nodes but missed the
virtual folders, so #1789 was closed prematurely; this completes it.
Reported and diagnosed by @fremat79.
Co-Authored-By: fremat79 <fremat79@users.noreply.github.com>
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
