Added:
- generate_particles_from_csv(...) plus common aliases
- CSV parsing via column names: m/mass, v1..v3, p1..p3
- conversion of string nan to numpy.nan
- particles_ascii_table(...)
- display_particles(...)
Verification:
- python3 -m py_compile particlecloud/utils.py passed.
- python3 -m unittest discover found 0 tests because tests/test_utils.py is not present.
- Runtime smoke test could not run because local NumPy fails to import due to an architecture
