Preserve entry positions in cache, bump when adding new ones

[tudddorrr]

No description provided.

[claude]

PR Review: Preserve entry positions in cache

After reviewing the changes, I found one issue that should be addressed:

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🟡 Code Quality

Position mutation of cached objects

The bump logic directly mutates the position field of cached LeaderboardEntry objects (LeaderboardEntriesManager.cs:40):

foreach (var e in entries)
{
    if (e.id != entry.id && e.position >= entry.position)
    {
        e.position += 1;  // Mutates cached object
    }
}

If external code holds references to these entries (via GetCachedEntries() or GetCachedEntriesForCurrentPlayer()), their positions will change unexpectedly when AddEntry is called. This creates potential confusion where a reference that was position=1 suddenly becomes position=2 without the holder knowing.

Suggested fix: Document this behavior in the method XML comments, or consider if entries should be immutable with a new instance created when positions change. Given the caching architecture, documentation is likely sufficient:

/// <summary>
/// Note: When bumpPositions=true, this method mutates the position field of existing cached entries.
/// </summary>
public void UpsertEntry(string internalName, LeaderboardEntry entry, bool bumpPositions = false)

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All other aspects look good - the implementation correctly handles the insert/update distinction, tests cover the new behavior thoroughly, and the change aligns with the PR's stated goal.