Read Many Files

Read several workspace files in one round trip.

One call resolves the sandbox once and checks its health once, where the same files read individually pay both per file. The response is the sandbox's own {"results": {path: envelope}} map, forwarded verbatim.

The ceiling is on the summed response rather than any one file, so a batch cannot relay more through this task than a single at-limit read already could. Over it, the caller sees the same too-large envelope a single read answers with -- no results key -- and is expected to fall back to reading the paths one at a time.