refactor(game): build small rounds around one fixed survivor boundary

[Joltras]

Proposed changes

A round with up to three survivors now counts as a small round in one fixed place instead of a setting. The number of pages, the extra hearts, the small speed boost and the healing steps all follow this one boundary. Before, the setting could be changed on its own and pull these parts apart, for example extra hearts without a small round. With the default settings nothing changes in game.

Types of changes

What types of changes does your code introduce to this project?
Put an x in the boxes that apply

• Bugfix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Documentation Update (if none of the other choices apply)

Checklist

Put an x in the boxes that apply. You can also fill these out after creating the PR. If you're unsure about any of
them, don't hesitate to ask. We're here to help! This is simply a reminder of what we are going to look for before
merging your code.

• I have read the CONTRIBUTING.md
• I have added tests that prove my fix is effective or that my feature works
• I have added necessary documentation (if appropriate)

[github-actions]

Test results

  672 files    672 suites   5m 5s ⏱️
1 516 tests 1 510 ✅  6 💤 0 ❌
4 551 runs  4 533 ✅ 18 💤 0 ❌

Results for commit 61be6db.

♻️ This comment has been updated with latest results.