Improved upcoming cards view

The current landing page of the Deck app shows only your upcoming cards based on due dates, which means that for people who don't use due dates the view in empty.

To make that better, we could have 2 views: one arranged by due dates like it currently exists, and one arranged by boards. This would allow for more flexibility in the landing page, and can also have some simple operations like adding boards and cards.

Here's a mockup that you can click around in:
https://www.figma.com/proto/76zsYNIXApcZA9ZqpXdJWb/Nextcloud_Deck_mockup?node-id=37%3A748&scaling=scale-down-width

• You can switch between the 2 views with a toggle, the default view for a user would be their last selected view, or board view if it's their first time

Board view

• The board view has a board in each column, arranged by date created, and an add board option at the end.
• You can add cards to a board, similar to the current way of adding cards to a list. The name would be entered as a text input, and the list it is in can be selected from a drop down menu of the existing lists in that board.
• Each board has its cards under it, sorted by due date if due dates are available, then by if that card is assigned to the user, then by last modified
• The card design would also be slightly different to indicate the name of the list it's in, and the last modified
• You can also add board from the board view by clicking on the add board button with the same flow as adding one from the sidebar.
• New boards can have 3 lists by default: To do, Doing and Done
• As soon as you add a board from the overview page, you are automatically prompted to add a new card

Due date view

• The due date view is similar to what currently exists, each column represents a time frame
• The cards under each column are grouped by the board they are in. In each group the cards are sorted the same way as the board view: first by due date, then by assigned cards, then by last modified
• If there are no due dates there is an empty content component

Review the current landing page and due-date view alongside the linked Figma mockup before identifying the relevant frontend entry points. Break the work into the view toggle, board and card creation flows, sorting rules, and due-date empty state. Done means both views match the listed behavior and all checklist items are covered.