COO-220 Initial scaffolding of cli tool for eregion

[prkrtg]

The CLI uses the typer library. Initially I was planning on using Python's argparse, however since prefect also uses typer , typer was a good option especially since I'm imagining the CLI over time does multiple subcommands, is config-driven, etc. Out of the box the library handles things we'd have to build by hand.

For the initial scaffolding of the cli tool, it calls the commands run and validate of the yaml file

Sample of using validate

% eregion validate src/eregion/configs/pipeline_flows/masterbias_example.yaml 
2026-08-10 21:40:43,132 - PipelineConfig - INFO - Config loaded from file 'src/eregion/configs/pipeline_flows/masterbias_example.yaml'
2026-08-10 21:40:43,132 - eregion.pipeline.engine - INFO - Number of pipelines defined: 2
2026-08-10 21:40:43,726 - eregion.pipeline.engine - INFO - Pipeline order: [('calib_flow',), ('preproc_flow',)]
2026-08-10 21:40:43,726 - eregion.pipeline.engine - INFO - Pipeline calib_flow order: [('calib_flow.image_creator',), ('calib_flow.master_bias',)]
2026-08-10 21:40:43,726 - eregion.pipeline.engine - INFO - Pipeline preproc_flow order: [('preproc_flow.image_creator', 'calib_flow.master_bias'), ('preproc_flow.bias_subtraction',), ('preproc_flow.overscan_subtraction',), ('preproc_flow.badpixel_masking',)]
Config OK: 2 pipeline(s) defined.

pipeline generation 0: ['calib_flow']
    [calib_flow] step 0: ['calib_flow.image_creator']
    [calib_flow] step 1: ['calib_flow.master_bias']
pipeline generation 1: ['preproc_flow']
    [preproc_flow] step 0: ['calib_flow.master_bias', 'preproc_flow.image_creator']
    [preproc_flow] step 1: ['preproc_flow.bias_subtraction']
    [preproc_flow] step 2: ['preproc_flow.overscan_subtraction']
    [preproc_flow] step 3: ['preproc_flow.badpixel_masking']

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