* fix(omp): negotiate RPC protocol v2 so large responses don't overflow
OMP caps protocol-v1 single-line RPC frames at 1 MiB. get_available_models
returns the full effective model catalog (hundreds of models), which exceeds
that cap, so OMP replies with an overflow error ("RPC response exceeded the
transport limit") and the OMP provider fails to start sessions.
Negotiate RPC protocol v2 after OMP's startup `ready` frame when it is
supported: v2 lifts the single-frame ceiling to 64 MiB by chunking oversized
frames. Add rpc_chunk reassembly to the shared JSONL transport so chunked
responses are reconstructed before routing, and gate the negotiation on the
ready frame so it is in place before the first request.
Protocol v2 is negotiated only when the peer advertises support in its ready
frame; peers that stay on v1 (e.g. Pi's --mode rpc) are unaffected.
* fix(omp): make protocol startup atomic
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Co-authored-by: pi3123 <pi3123@users.noreply.github.com>
Co-authored-by: Mohamed Boudra <boudra.moha@gmail.com>
