Jira export, table sorting and document links

✨ New

Export to Jira — The mirror flow of the import: mapping of users, trackers, statuses, versions, priorities and tags, then a summary. Settings now separate "Imports" and "Exports".

Table sorting — Pick a field and a direction; the sort is remembered on the board.

Document ↔ task link — Referencing a task in a document creates a "Mentioned by" link, visible from the task.

Bulk task creation — A "Create another task" checkbox keeps the window open and clears the title.

Context menu in the table view — Change a property value straight from its row.

🚀 Improvements

• Status and target version show as tags, and priority with its icon.
• List fields show their colour in the table view.
• A list or member field can be cleared again thanks to an empty option.
• The active grouping is highlighted in its menu.
• "Cancel" buttons move to a secondary style to set the primary action apart.
• A completion report shows how many tasks were imported or exported, and how many already existed.

🐛 Fixes

• An oversized attachment failed silently; the message now names the rejected files.
• Subtask display and handling.
• Scheduled session refreshes were not cancelled when switching project or board.