Convert sqlite.py into an idempotent DB setup script

[Neha20072002]

Convert sqlite.py into an idempotent DB setup script

Wrap execution in if name == "main" and add logic to create the table only if it does not exist; avoid inserting duplicates.
Provide CLI flags to recreate vs append (optional).
File: sqlite.py.

[princexpoddar]

Kindly assign this issue to me under Hacktoberfest