Raise FileNotFoundError from archive ls for a missing path

[itzzdev09]

AbstractArchiveFileSystem.ls (used by zip, tar and libarchive) returns [] in two cases where other filesystems don't:

fs = fsspec.filesystem("zip", fo="archive.zip")   # contains "b" and "deeply/nested/path"

fs.ls("i-do-not-exist")   # [] -- expected FileNotFoundError
fs.ls("b")                # [] -- expected [info of "b"]

info("i-do-not-exist") already raises FileNotFoundError on the same filesystem, and LocalFileSystem, MemoryFileSystem and the object stores raise from ls too. Returning an empty list makes a typo look like an empty directory.

Change

When nothing is listed under a non-root path, ls now falls back to info:

• a missing path raises FileNotFoundError;
• a file is listed as itself;
• an empty directory still returns [].

Listing the root of an empty archive still returns [] (test_empty), and listings that find entries are unchanged.

Tests

Added TestAnyArchive.test_ls_file_or_missing, which runs for zip, tar, tar.gz, tar.bz2, tar.xz and libarchive. It fails against master's archive.py for every scenario that runs here (libarchive isn't installed locally, so it's skipped) and passes with the change. test_archive.py, test_zip.py, test_tar.py, test_libarchive.py and fsspec/tests/test_api.py: 193 passed, 21 skipped. ruff 0.14.3 check and format are clean.

🤖 Generated with Claude Code

[itzzdev09]

CI caught a test I hadn't run: test_dirfs.py::test_find_detail_single_tar_file (from #2127) asserted that find on a single tar member returns the {} placeholder the base find falls back to when ls is empty. Now that ls lists a file as itself, find returns the member's real info, the same as on other filesystems, so 4118cce updates that test to check the name, type and size instead. The no-name fallback in dirfs is still covered by test_detail_without_name. I compared the full suite against master locally, and that test was the only difference.