fep(sig-network): Add FlagCX v0.13.0 new features

[MC952-arch]

Comparing v0.13.0 (current main branch) against v0.11.0 (commit cceb96d), three significant feature areas have been introduced in FlagCX:

1. P2P Engine — a one-sided RDMA engine for point-to-point communication, enabling prefill-decode disaggregation in LLM inference scenarios and NIXL integration.
2. Device API-based CustomAllReduce — an intra-node AllReduce collective implemented entirely through FlagCX Device API primitives, allowing custom kernels to perform AllReduce without host-side scheduling overhead.
3. Device API IR Bindings for Triton — a set of C IR wrapper functions (compilable via LLVM bitcode) that expose FlagCX device-side communication primitives to Triton-generated kernels.