GHSA-m2p3-hwv5-xpqw: Scriban: Denial of Service via Unbounded Cumulative Template Output Bypassing LimitToString

The LimitToString safety limit (default 1MB since commit b5ac4bf) can be bypassed to allocate approximately 1GB of memory by exploiting the per-call reset of _currentToStringLength in ObjectToString. Each template expression rendered through TemplateContext.Write(SourceSpan, object) triggers a separate top-level ObjectToString call that resets the length counter to zero, and the underlying StringBuilderOutput has no cumulative output size limit. An attacker who can supply a template can cause an out-of-memory condition in the host application.