fix(napi): Use strong consistency for the entire project_trace_source function (#79917)
This function does a few more `Vc` reads than just looking up the source map, so it's better to move the entire thing inside one strongly-consistent operation.
This was an attempt to fix a loop (tracing an error -> react fast refresh -> triggers the same error again -> ...) https://vercel.slack.com/archives/C046HAU4H7F/p1747837763588429, though it doesn't seem like this fixes it.