- Root handler now only serves the welcome page for GET/HEAD; all other
methods (e.g. OPTIONS, PROPFIND) return 405 with an Allow header instead
of always returning 200, fixing client capability probes and PROPFIND
misbehavior.
- Mount /files/ properly and cache one xwebdav.Handler per authenticated
user so its LockSystem persists across requests instead of being
recreated per-request (which broke LOCK/UNLOCK).
- Remove the username segment from all DAV URLs (/cal/, /card/, /files/
are now identical for every account; the acting user is always resolved
via Basic Auth, never the path).
- Reintroduce a fixed literal "home" path segment (/cal/home/,
/card/home/) to preserve the URL segment depth that go-webdav's
caldav/carddav server relies on to classify resources (principal vs.
home-set vs. collection vs. object). Removing the username had
collapsed this depth, silently misclassifying requests and returning
empty <multistatus> responses (DAVx5 "no resources found").
- Replace the store's single global mutex with per-user sharded locks so
different users' requests no longer serialize against each other.
- Add auth.NewContext test helper, WebDAV handler tests
(per-user isolation, lock persistence across requests), and a
concurrent multi-user store test.
- Update README and copilot-instructions to document the new URL scheme
and the go-webdav path-depth classification quirk.
Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>