feat: add card dependencies

[luka-nextcloud]

• Resolves: Dependencies / Subtasks for cards #5346
• Target version: main

Summary

Introduces the concept of "dependent cards", allowing users to assign and remove dependencies between cards. The implementation includes backend support, API routes, database migration, and frontend UI integration for managing card dependencies.

Checklist

• Code is properly formatted
• Sign-off message is added to all commits
• Tests (unit, integration, api and/or acceptance) are included
• Documentation (manuals or wiki) has been updated or is not required

[github-actions]

🐢 Performance warning.
It looks like the query count of the integration tests increased with this PR.
Database query count is now 95978 was 93102 (+3.08%)
Please check your code again. If you added a new test this can be expected and the base value in tests/integration/base-query-count.txt can be increased.

[github-actions]

🐢 Performance warning.
It looks like the query count of the integration tests increased with this PR.
Database query count is now 96859 was 93102 (+4.03%)
Please check your code again. If you added a new test this can be expected and the base value in tests/integration/base-query-count.txt can be increased.

[github-actions]

🐢 Performance warning.
It looks like the query count of the integration tests increased with this PR.
Database query count is now 96819 was 93102 (+3.99%)
Please check your code again. If you added a new test this can be expected and the base value in tests/integration/base-query-count.txt can be increased.

[github-actions]

🐢 Performance warning.
It looks like the query count of the integration tests increased with this PR.
Database query count is now 96814 was 93102 (+3.98%)
Please check your code again. If you added a new test this can be expected and the base value in tests/integration/base-query-count.txt can be increased.

[DesertCookie]

Awesome to see some movement on this.

[luka-nextcloud]

Recording video:

demo.mp4

[github-actions]

🐢 Performance warning.
It looks like the query count of the integration tests increased with this PR.
Database query count is now 96891 was 93102 (+4.06%)
Please check your code again. If you added a new test this can be expected and the base value in tests/integration/base-query-count.txt can be increased.

[grnd-alt]

didn't review everything yet. It basically works, but looking at the comment in the migration step, I think this part needs a rework.

[github-actions]

🐢 Performance warning.
It looks like the query count of the integration tests increased with this PR.
Database query count is now 97505 was 93102 (+4.72%)
Please check your code again. If you added a new test this can be expected and the base value in tests/integration/base-query-count.txt can be increased.