Split evaluation.md into scoring + presentation

[glacierphonk]

Problem

evaluation.md is 220 lines — the largest reference file. It covers two distinct phases:

1. Scoring (rubric, weights, template) — needed in Step 6
2. Presentation (sentence tests, side-by-side comparison, 24-hour test, decision format) — needed in Step 7

Loading the entire file in Step 6 wastes context on presentation guidance that isn't needed until Step 7.

Fix

Split into:

1. evaluation.md (~120 lines) — scoring rubric, weights, template, pre-scoring gate, tiebreakers
2. presentation.md (~100 lines) — sentence tests, side-by-side comparison, 24-hour test, decision format

Update SKILL.md:

• Step 6 loads `evaluation.md`
• Step 7 loads `presentation.md`

Before submitting

Read CONTRIBUTING.md and run `markdownlint-cli2 '**/*.md'` before pushing.

Scope

Split one file into two + update references. Medium PR.