fix: add table of contents to all reference files

Per Anthropic's Agent Skills best practices, reference files over
  100 lines should include a TOC so Claude can see full scope when
  previewing with partial reads. Added ## Contents section to all
  32 reference files.

skills/copywriting/references/copy-frameworks.md

@@ -2,6 +2,12 @@
 
 Headline formulas, page section types, and structural templates.
 
+## Contents
+- Headline Formulas (outcome-focused, problem-focused, audience-focused, differentiation-focused, proof-focused, additional formulas)
+- Landing Page Section Types (core sections, supporting sections)
+- Page Structure Templates (feature-heavy page, varied engaging page, compact landing page, enterprise/B2B landing page, product launch page)
+- Section Writing Tips (problem section, benefits section, how it works section, testimonial selection)
+
 ## Headline Formulas
 
 ### Outcome-Focused

skills/copywriting/references/natural-transitions.md

@@ -6,6 +6,26 @@ Adapted from: University of Manchester Academic Phrasebank (2023), Plain English
 
 ---
 
+## Contents
+- Previewing Content Structure
+- Introducing a New Topic
+- Referring Back
+- Moving Between Sections
+- Indicating Addition
+- Indicating Contrast
+- Indicating Similarity
+- Indicating Cause and Effect
+- Giving Examples
+- Emphasising Key Points
+- Providing Evidence (neutral attribution, expert quotes, supporting claims)
+- Summarising Sections
+- Concluding Content
+- Question-Based Transitions
+- List Introductions
+- Hedging Language
+- Best Practice Guidelines
+- Transitions to Avoid (AI Tells)
+
 ## Previewing Content Structure
 
 Use to orient readers and set expectations: