Finish the review: spells/skills rulebook fidelity + test-quality pass

[StreamDemon]

This follow-up owns the rulebook-fidelity and test-quality lenses that remained
incomplete in docs/reviews/2026-07-03-rules-layer-review.md.

Current baseline (2026-07-18):

• 156 spells covering levels 1–15, including 15 finite spells with structured damage
  effects;
• 45 skills; and
• 309 tests across 19 files.

Issue #13 is closed, so this review applies to the complete current spell catalog
rather than the original levels 1–4 slice.

Scope:

1. Review all 156 spells against rendered rulebook pages for names, levels, P.P.E.,
   range, duration, saving throws, prose, and structured finite damage.
2. Review all 45 skills against rendered pages for base values, per-level gains,
   secondary values, prerequisites, repeatability, and notes.
3. Review test quality across the current suite for meaningful assertions, boundary
   coverage, regression value, and unjustified snapshots or tautologies.

Review page by page using docs/rules/TRANSCRIPTION.md and the printed-page index in
docs/rules/PAGE_MAP.md. Preserve evidence and page citations for every correction.
The dated July 3 review keeps the historical counts; this issue is the current owner
for the remaining fidelity and test-quality work.