fix: remove mock cards in app.py

feat: expand ISO 639-1 language mapping to 23 EU languages

test: remove obsolete csv_for_anki_test.py, keep apkg_export_test.py

feat: add apkg_export.py with genanki-based .apkg export

test: add failing tests for apkg_export module

refactor: remove deprecated apkg_generator module and tests

test: add comprehensive tests for csv_for_anki module

fix: retry with apkg export files

test: update widget tests for APKG export components

feat: add APKG generate_apkg_package end-to-end function

feat: add APKG media injection with MD5 hashing and deduplication

feat: add APKG package generation with genanki and deck naming

feat: add APKG note creation with HTML escaping and media references

feat: add APKG model creation with genanki

fix: reseting to correct state when changing language

feat: restore Generate Cards button on parameter change after Phase 2

fix: exporting files

fix: single-click export download and remove export status label

refactor: flatten export folder and rename media files with meaningful names

fix: export csv works

feat: wire CSV/APKG export into UI with gr.File download

feat: implement csv_export with zip download support and tests

feat: test use pytest and test all modules

refactor: rename scripts/ to tests/ with pytest-compatible naming