windows: add chromewebstore to UNIX_ONLY_PROVIDER_NAMES

CRX extraction on Windows needs either POSIX unzip (not present)
or a bundled unzipper npm package (not currently bundled). The
in-process CRX-header strip + tar -xf fallback I tried isn't
working reliably on the Windows runners. Until someone bundles
unzipper or a pure-JS extractor, treat chromewebstore like
the other Unix-only providers — drop it from
DEFAULT_PROVIDER_NAMES on Windows and let the conftest skip
filter elide test_chromewebstoreprovider.py.

Author: claude

abxpkg/windows_compat.py

@@ -40,8 +40,20 @@
 # when ``IS_WINDOWS`` is true. ``scoop`` takes brew's place on Windows.
 # ``docker`` is excluded because its install handler writes a ``/bin/sh``
 # shim; the CLI itself works fine once installed outside abxpkg.
+# ``chromewebstore`` needs POSIX ``unzip`` (or a bundled ``unzipper``
+# npm dep) to unpack ``.crx`` files; neither is reliably available on
+# Windows runners, so disable until that's addressed.
 UNIX_ONLY_PROVIDER_NAMES: frozenset[str] = frozenset(
-    {"apt", "brew", "nix", "bash", "ansible", "pyinfra", "docker"},
+    {
+        "apt",
+        "brew",
+        "nix",
+        "bash",
+        "ansible",
+        "pyinfra",
+        "docker",
+        "chromewebstore",
+    },
 )
 
 # Mirrors the 7-tuple layout of :class:`pwd.struct_passwd` so Unix and