Bug 2048968 - Add ordering for links and shares

[nathan-barrett]

Adds a new position property so that shares are listed in the order they were shared

Docs:

• https://docs.djangoproject.com/en/6.0/ref/models/options/#ordering
• https://docs.python.org/3/library/heapq.html#heapq.merge

[fterdal]

This looks good! It works for me locally, and the position Meta field is cool 😎. The only thing I'd mention is that there's no obvious way to break ties if two links have the same position.

This shouldn't happen in practice going forward, since new link collections will be passed a position determined by the index. But seeded data (or database rows that gets into a weird state for some reason 🤷🏻) might show up in an unpredictable order.

Links don't have a created_at field to break ties either, and I don't think it's worth adding one just for this purpose.

✅ r+ – This is good to go, just mentioning this here in case we care about tie-breaking behavior in the future.

[nathan-barrett]

good point! wonder if we'd need tie breaking at any point 🤔