[NanoCtrl, PeerAgent] fix scope name logic

[JimyMa]

Summary

Fix PeerAgent alias registration and scope discovery behavior in the NanoCtrl control plane.

Motivation

PeerAgent aliases are scoped identifiers. Agents in different scopes should be allowed to use the same alias, but two agents in the same scope should not silently overwrite each other in Redis.

Previously, duplicate aliases could overwrite the same agent:{alias} key, making two PeerAgents appear as one agent and causing confusing connection/read behavior.

Changes

• Add NanoCtrl/lua/register_agent.lua for atomic PeerAgent registration.
• Reject duplicate PeerAgent aliases within the same scope.
• Preserve support for the same alias across different scopes.
• Load the new Lua script through LuaScripts.
• Add PeerAgent-side self-alias rejection in connect_to().
• Add tests for:
  • self-alias connection rejection
  • scope-isolated discovery with the same alias in different scopes
• Update the control-plane RDMA read example to use distinct aliases and a shared scope.

Validation

cargo fmt
cargo check
pytest -q tests/python/test_peer_agent_topology_discovery.py
python -m py_compile dlslime/peer_agent/_agent.py examples/python/p2p_rdma_rc_read_ctrl_plane.py