Fix unnecessary leaderboard entry position bumping

[tudddorrr]

No description provided.

[claude]

This fix is correct and the logic is sound. A few observations:

---

🔵 Minor: Loop bumps entries beyond the collision unnecessarily

The new loop runs from collisionIndex to the end of the list, bumping all subsequent entries — including those at positions well beyond the collision point.

For example: entries [A@0, B@1, C@3], upsert D@1:

• D inserts, collisionIndex points to B@1
• Loop bumps B@1→2 (correct) and C@3→4 (unnecessary — no entry displaced C)

The old foreach had identical behaviour, so this is pre-existing rather than a regression. But the new code was an opportunity to fix it too:

// Only bump entries that are contiguous with the collision
for (int i = collisionIndex; i < entries.Count; i++)
{
    if (entries[i].id == upsertEntry.id) continue;
    if (i > collisionIndex && entries[i].position != entries[i - 1].position + 1) break;
    entries[i].position += 1;
}

Whether that scope belongs in this PR is a judgment call — the stated fix (no-bump on same-position improvement) is correct as-is.

---

🔵 Minor: Missing test for a displaced entry scenario

The new test only covers the "no collision" path. There is no test verifying that entries at positions above the collision are (or are not) bumped when a genuine displacement occurs. The existing UpsertEntry_BumpPositions_OnlyBumpsAffectedEntries may cover this, but it predates the refactor so it is worth confirming it still exercises the new code path correctly.

---

Overall the core fix — using FindIndex for a collision check rather than bumping on position >= entry.position — is correct and well-targeted.