CVE-2026-53531: ratex-parser has unbounded parser recursion that leads to stack overflow (process abort)

RaTeX’s recursive-descent parser recurses one (or more) native stack frame per nesting level at {, \left, \sqrt{, ^{, etc, with no maximum depth limit. A short, ~10 KB input of nested groups overflows the 8 MB main-thread stack and aborts the process. With panic = "abort" (Cargo.toml:48), and because a Rust stack overflow is always a fatal SIGABRT regardless of panic strategy this is an unrecoverable, whole-process denial of service reachable from a single untrusted LaTeX string.