fix(test): correct entry variants fetch_nonexistent to use fetch(uid) pattern

variants(x) treats its single positional arg as a branch UID, not a
variant UID, so variants("no_such_variant").fetch() left variant_uid=None
and hit the client-side ArgumentException guard before the HTTP call.
Fix: pass the UID to fetch() directly, which is the correct SDK pattern.

Generated by Claude Code

Author: aniket-shikhare-cstk

tests/integration/api/test_17_entry_variants.py

@@ -36,6 +36,7 @@ def test_include_variants_requires_variant_uid(self, stack, entry_ctx):
 class TestEntryVariantsNegative:
     def test_fetch_nonexistent(self, stack, entry_ctx):
         ct_uid, entry_uid = entry_ctx
-        resp = stack.content_types(ct_uid).entry(entry_uid).variants("no_such_variant").fetch()
+        # variants(x) treats x as branch, not variant_uid — pass uid to fetch() instead.
+        resp = stack.content_types(ct_uid).entry(entry_uid).variants().fetch("no_such_variant")
         # Variants API returns 412 (precondition failed, code 1010) for unknown variant.
         h.assert_status(resp, 404, 412, 422)