Python/FastAPI port of CBSA — full re-architecture

[DukeDeSouth]

Hi,

I've re-architectured the CBSA application from COBOL/CICS/DB2 to Python/FastAPI/SQLite as a learning exercise and proof of concept.

What's in the port:

• All 11 business programs (DBCRFUN, XFRFUN, CRECUST, CREACC, INQCUST, INQACC, INQACCCU, UPDCUST, UPDACC, DELACC, DELCUS) translated to Python service functions
• 9 BMS screens replaced by a single-page web UI
• DB2 + VSAM replaced by SQLite (money stored as INTEGER cents to match COBOL precision)
• CRDTAGY1-5 async credit check replaced by ThreadPoolExecutor
• Test data generator based on BANKDATA.cbl arrays
• 19 pytest tests, 15 REST API endpoints

Repo: https://github.com/DukeDeSouth/ibm-cics-banking-python

The COBOL source is included unchanged under EPL-2.0. Happy to answer questions or hear feedback on the approach.