Board export is incomplete for archived cards and card metadata

The current board export is not a complete representation of a board. This is especially relevant when exports are used for backups, reporting, statistics, audits, or external tools such as Power BI.

Current behavior

• Archived cards are not included in the frontend board export.
• Re-importing an exported JSON board therefore does not fully restore the original board state.
• The configured done column is present in the exported data but is not restored by the JSON importer.
• The CSV export only contains a small subset of card data.
• The CSV export does not include stable IDs such as card ID or stack/list ID.
• The CSV export does not include card completion state or completion date.
• The CSV export does not include all relevant date fields, for example start date.
• Date/time values are exported inconsistently: some fields are localized dates only, while due dates are exported as raw values.

Expected behavior

The board export should contain enough data to represent the board state completely and unambiguously.

At minimum, exports should include:

• archived cards
• card ID
• stack/list ID
• archived state
• done/completed state
• completion date
• due date
• start date
• created date and time
• last modified date and time

For JSON, the exported data should be suitable for restoring the board state as completely as possible. For CSV, the exported data should be useful for external processing and reporting.

Discussion

I'd be happy to submit a PR addressing those issues, however, beforehand, I'd like to discuss this a bit. Is the current behavior intentional or is it just not implemented well?

In particular:

• Is the board export intended to exclude archived cards?
• Is there a technical reason why archived cards are not included in the regular board export?
• Is the CSV export intentionally limited to a lightweight summary?
• Are there import compatibility, performance, or privacy concerns around exporting the missing metadata?
• Should JSON and CSV expose the same logical card data, even if their structure differs?

Start by locating the frontend board export, JSON importer, and CSV export entry points; compare the fields each currently handles with the issue's minimum list. Check how archived cards and the done column are represented, then define completion as exports containing the required stable IDs, states, and dates and JSON restoring the board state as completely as possible.