feat(skills): add marketing skills collection

shared/skills/copy-editing/references/checklist.md

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+# Copy Editing Checklist
+
+Use this checklist alongside the Seven Sweeps Framework (see SKILL.md) as a final QA pass before delivering edited copy.
+
+## Before You Start
+
+- [ ] Understand the goal of this copy
+- [ ] Know the target audience
+- [ ] Identify the desired action
+- [ ] Read through once without editing
+
+## Clarity (Sweep 1)
+
+- [ ] Every sentence is immediately understandable
+- [ ] No jargon without explanation
+- [ ] Pronouns have clear references
+- [ ] No sentences trying to do too much
+
+## Voice & Tone (Sweep 2)
+
+- [ ] Consistent formality level throughout
+- [ ] Brand personality maintained
+- [ ] No jarring shifts in mood
+- [ ] Reads well aloud
+
+## So What (Sweep 3)
+
+- [ ] Every feature connects to a benefit
+- [ ] Claims answer "why should I care?"
+- [ ] Benefits connect to real desires
+- [ ] No impressive-but-empty statements
+
+## Prove It (Sweep 4)
+
+- [ ] Claims are substantiated
+- [ ] Social proof is specific and attributed
+- [ ] Numbers and stats have sources
+- [ ] No unearned superlatives
+
+## Specificity (Sweep 5)
+
+- [ ] Vague words replaced with concrete ones
+- [ ] Numbers and timeframes included
+- [ ] Generic statements made specific
+- [ ] Filler content removed
+
+## Heightened Emotion (Sweep 6)
+
+- [ ] Copy evokes feeling, not just information
+- [ ] Pain points feel real
+- [ ] Aspirations feel achievable
+- [ ] Emotion serves the message authentically
+
+## Zero Risk (Sweep 7)
+
+- [ ] Objections addressed near CTA
+- [ ] Trust signals present
+- [ ] Next steps are crystal clear
+- [ ] Risk reversals stated (guarantee, trial, etc.)
+
+## Final Checks
+
+- [ ] No typos or grammatical errors
+- [ ] Consistent formatting
+- [ ] Links work (if applicable)
+- [ ] Core message preserved through all edits