Add indented card examples

Fix inconsistent formatting

Decouple shared parser/cli logic into util file

Normalize whitespace ltrim, fix signed char UB for isDigit

Fix extension check to be case-insensitive

Merge branch 'main' of github.com:Jaefae/md2anki

Fix reversed card extra comma

Fix csv parsing for tag collection

Fix answer pair parsing to be case-agnostic

Modify feature list

Add larger example

Main cli interaction loop

Remove header mode from cli

Add parser implementation

Fix card constructor signature and switch break indent.