bug: saving files assumes PDF data is being analyzed even if its not PDF data #282

Problem

This was pointed out by Paola when morphing iq data in the form of .dat files. When files are saved, the columns are labeled as r and gr like this # Labels: [r] [gr]. In the metadata, there is also the line that says # PDF created by diffpy.morph. the files are also saved as .cgr files even if its not PDF. In summary, this is what the header looks like of a saved morph file:

# PDF created by diffpy.morph
# from /Users/cadenmyers/billingelab/BNL/oct2025_beamtime/data/Xiaoyu/gr/rt/TiSe2_RT_XS4_215C_PDF_20251021-124802_1da6c1_sum.gr

# Labels: [r] [gr]
0.000000000000000000e+00 0.000000000000000000e+00
1.000000000000000021e-02 -2.563058786130854593e-06
2.000000000000000042e-02 -1.912763583912635416e-05

Proposed solution

Fix this to infer spectrum type from the filename (.iq, .fq, .gr, etc)

1. changed # PDF created by diffpy.morph to # file created by diffpy.morph
2. Use input file suffix to determine if its a PDF (ie if "gr" in str(path_object.stem) or something). If not gr, have some sort of default behavior