Add Python interface (pyquick) via f2py

[vtripath65]

Summary

This PR adds pyquick, a Python interface to QUICK built with f2py, enabling
users to set up and run QUICK calculations directly from Python without writing
input files.

New files

• src/pyquick/pyquick.f90 — Fortran module compiled by f2py into a Python C
  extension. Exposes subroutines for setting the calculation type, basis set,
  method keywords, and molecular geometry, as well as running the SCF and
  retrieving results (total energy, MO energies, density matrix, Mulliken/Löwdin
  charges).
• src/pyquick/__init__.py — Pure-Python wrapper that imports the f2py extension,
  checks the had_error flag after every Fortran call and raises RuntimeError
  on failure, and provides the PyQuick class with per-instance state and a
  copy() method for creating independent conformations.
• src/pyquick/CMakeLists.txt — Build rules for the f2py extension. Before
  attempting to compile, the build system explicitly checks that both Python and
  numpy (including f2py) are available via find_program and
  execute_process. A clear FATAL_ERROR is emitted if either is missing,
  rather than failing silently at compile time.

Build system changes

• CMakeLists.txt — adds -DPYTHON=TRUE option.
• src/CMakeLists.txt — adds add_subdirectory(pyquick) guarded by
  -DPYTHON=TRUE.
• quick-cmake/quick.rc — prepends <prefix>/lib to PYTHONPATH so that
  import pyquick works after source quick.rc.

Build instructions

cmake .. -DCOMPILER=GNU -DENABLEF=FALSE -DPYTHON=TRUE \
         -DCMAKE_INSTALL_PREFIX=$PWD/../install
cmake --build . --parallel $(nproc)
cmake --install .
source ../install/quick.rc

Usage example

from pyquick import PyQuick

job = PyQuick()
job.set_calc('HF')
job.set_basis('STO-3G')
job.read_geom('''
    O  0.000  0.000  0.000
    H  0.757  0.586  0.000
    H -0.757  0.586  0.000
''')
job.run()
print(job.total_energy)

# Copy a job and modify independently
job2 = job.copy()
job2.read_geom('''
    O  0.100  0.000  0.000
    H  0.857  0.586  0.000
    H -0.657  0.586  0.000
''')
job2.run()
print(job2.total_energy)

[agoetz]

Converted this to draft so we don't merge it before releasing QUICK-26.03