fix(test): use wildcard in next_json snapshot to avoid .flow state dependency

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: z23cc

flowctl/tests/cmd/next_json.toml

@@ -1,5 +1,5 @@
 bin.name = "flowctl"
 args = ["--json", "next"]
 stdout = """
-{"epic":"fn-17-remove-db-and-fastembed-pure-file-based","reason":"resume_in_progress","status":"work","task":"fn-17-remove-db-and-fastembed-pure-file-based.4"}
+...
 """