CVE-2026-47770: jq: stack overflow in deep structural equality

jq is a command-line JSON processor. Prior to 1.8.2, comparing two sufficiently deeply nested arrays with the == operator exhausts the C stack on jq's ordinary command-line surface, resulting in denial of service via stack exhaustion (uncontrolled recursion). The crash occurs in jq's recursive structural comparison code, with the recursion repeating through jvparrayequal() and jvequal() in src/jv.c when comparing deeply nested arrays; a nearby sort comparator path through jvcmp() in src/jvaux.c overflows the stack at a larger nesting depth from the same missing recursion guard. Anyone running jq comparisons on attacker-controlled deeply nested JSON values, or embedding jq in a context where untrusted data can reach the == comparison path, is affected. This vulnerability is fixed in 1.8.2.