Only average scripture confidences for per-book confidence

[Enkidu93]

Fixes #1033.

---

This change is 

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 72.61%. Comparing base (43ffd54) to head (ce5e35b).

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1034      +/-   ##
==========================================
+ Coverage   72.59%   72.61%   +0.01%     
==========================================
  Files         391      391              
  Lines       21676    21677       +1     
  Branches     2820     2820              
==========================================
+ Hits        15735    15740       +5     
+ Misses       4814     4810       -4     
  Partials     1127     1127              

☔ View full report in Codecov by Harness.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.
• 📦 JS Bundle Analysis: Save yourself from yourself by tracking and limiting bundle sizes in JS merges.

[pmachapman]

@pmachapman reviewed 2 files and all commit messages, and made 1 comment.
Reviewable status: complete! all files reviewed, all discussions resolved (waiting on Enkidu93).