Add flatmap_diagnostic.py CLI for validation/diagnostics #170

To validate the integrity and completeness of flatmap source data and the maps generated from it.

Inputs:

• Manifest files of the source flatmap (--manifest-files)
• Generation log files (--log-files)

Outputs:

• node_complete – full node validation results
• node_minimal – minimal node validation results
• paths_minimal – minimal path validation results
• source_check – summary of source data checks

CLI Options:
--manifest-files : Path(s) to manifest files
--log-files : Path(s) to generation log files
--output-dir : Directory where output validation results are saved

Description:
This task ensures that the flatmap source data is complete and consistent, and that the maps generated from it match expectations. The tool should process the manifests and logs, and produce a structured set of output files for further analysis or automated checks.