add support for fits: open, getheader, getval, getdata

csst_common/fits.py

+"""
+Identifier:     csst_common/fits.py
+Name:           fits.py
+Description:    IO module
+Author:         Bo Zhang
+Created:        2025-10-23
+Modified-History:
+    2025-10-23, Bo Zhang, created, support FITS operations for s3
+"""
+
 from astropy.io import fits
 from csst_fs.s3_config import load_s3_options