Add configurable tiebreak rules for round-robin standings

[Nat004499]

Description

In round-robin stages, teams with equal ranking points currently do not seem to have configurable tiebreak rules.

For many sports tournaments, this is important because different sports or organizers may use different priorities to break ties.

For example, a common order could be:

1. Ranking points
2. Number of wins
3. Point difference
4. Points scored
5. Head-to-head

However, some sport or tournament might want a different order.

Expected behavior

It would be useful to support configurable tiebreak rules for round-robin stages.

Possible tiebreak criteria could include:

• Ranking points
• Number of wins
• Number of draws
• Point difference
• Points scored
• Points conceded
• Head-to-head result
• Alphabetical order / manual fallback

These criteria should ideally be reorderable.

UI proposal

When creating or editing a round-robin stage item, the user could configure the tiebreak order through the UI.

For example:

• A list of selected tiebreak criteria
• Drag-and-drop to reorder criteria
• Ability to enable/disable criteria
• A sensible default order

Example default:

1. Ranking points
2. Wins
3. Point difference
4. Points scored

Why this matters

Without configurable tiebreak rules, round-robin standings may be unsuitable for real sports tournaments where official ranking rules must be followed.

This is especially important when the standings are used to automatically seed the next stage.