ENH: Support sockets for NWChem

[HaoZeke]

Basically a manyfold increase compared to the existing ASE wrapper. Over 16 steps of a minimization times are:

40s with unix sockets
47s with TCP/IP
78s with ASE

This implements an independent "server" which implements enough of the i-Pi protocol to talk to NWChem. Closes #247.

[HaoZeke]

Best to wait until nwchemgit/nwchem#1145 with which times go down to around 17s (with a local build including scalapack).

[Copilot]

Pull Request Overview

This PR implements a socket-driven NWChem potential that provides significant performance improvements over the existing ASE wrapper by communicating directly with NWChem using the i-PI protocol.

• Adds SocketNWChemPot class that implements TCP/IP and UNIX domain socket communication with NWChem
• Refactors ZBL potential parameter handling to use structured options approach
• Includes comprehensive test infrastructure and example configurations

Reviewed Changes

Copilot reviewed 26 out of 27 changed files in this pull request and generated 6 comments.

Show a summary per file

File	Description
eon/schema.py	Adds SocketNWChemPot configuration schema and updates ZBL parameter formatting
eon/config.yaml	Adds SocketNWChemPot configuration options
client/potentials/SocketNWChem/*	Core implementation of socket-based NWChem potential with header, source, and build files
client/potentials/ZBL/ZBLPot.cpp	Updates to use structured ZBL options from parameters
client/Parameters.*	Adds socket_nwchem_options struct and refactors ZBL options
client/BaseStructures.h	Adds SocketNWChem to PotType enum
client/gtests/*	Comprehensive test infrastructure for socket NWChem functionality

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[HaoZeke]

Needs some documentation for later, but generally with rgpycrumbs this is fairly easy to work with:

generate_nwchem_input.py
mpirun -np 8 /home/rgoswami/Git/Github/Fortran/nwchem/bin/LINUX64/nwchem nwchem_socket.nwi
# other terminal
eonclient

where a good default for the nwchem_settings.nwi is

basis noprint
  * library 3-21G
end

scf
  nopen 0
  thresh 1e-8
  maxiter 200
end