Credit Card Transaction System

Implement a simple in-memory credit-card transaction system that processes a batch of commands and returns a summary report. Each command is a single space-separated string of the form “action card amount”. The three actions are:

• new <card> <limit> – create a new account with the given card number and credit limit. If the card number is not exactly 12-16 digits (regex ^[0-9]{12,16}$) the command is silently ignored.
• debit <card> <amount> – withdraw the given amount. The debit is rejected (silently skipped) if it would drive the account balance below –limit; otherwise the balance is decreased by amount.
• credit <card> <amount> – add the given amount to the account balance.

The system must maintain an internal map from card number to current balance and credit limit. Commands referencing a card that was never successfully created, or that fail validation, are ignored. After every command has been processed, produce a summary report: a list of all active cards in lexicographic order, each followed by its current balance. The balance may be negative (indicating owed money) but may never go below –limit. The report is returned as a list of strings, one per card, formatted as “<card>: <balance>”.