ListDirectory now appends a synthetic <viewer-email>/ entry when the
listed path is exactly <project>/working/ (depth 2, case-fold) and no
real directory there matches the viewer's email under any case.
The entry has IsDir=true and a new Virtual=true flag on
listing.FileInfo (omitempty in JSON so existing clients that don't
know the field continue to render it as a regular folder). A first
write to that path materialises a real folder via the existing
auto-own pipeline (EnsureCanonicalAncestors → WriteAutoOwnZddc),
after which subsequent listings drop the synthetic entry naturally.
Anonymous viewers, listings outside working/, and listings inside a
deeper working/ subdirectory all skip the synthetic entry.
Six tests cover: appears-when-missing, suppressed-when-real-exists
(case-fold), anonymous-no-entry, staging/-no-entry, deep-working-no-
entry, and pre-existing-PascalCase-Working/ still triggers it.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
