feat: 100 skills milestone — 7 new skills + quality improvements across all 93

New skills added:
- teaching-lesson-plan: structured lesson plans for any subject/audience/setting
- seo-content-brief: complete SEO briefs with intent, competitor gaps, and outline
- media-pitch: story-first journalist pitches with angle development framework
- change-management-plan: stakeholder analysis, comms strategy, adoption metrics
- workshop-facilitation-guide: activity instructions, decision protocols, facilitator moves
- sales-forecasting-model: pipeline model, scenario analysis, assumption log
- tax-planning-checklist: year-end tax planning across income, pension, CGT, reliefs

Quality improvements across all 93 existing skills:
- Standardised description format: "Verb the thing. Use when X. Produces Y."
- Added Required Inputs section to all skills missing it (prompts for missing info)
- Added Quality Checks section to all skills missing it (specific, not generic)
- Fixed broken multiline YAML descriptions
- Removed non-standard frontmatter keys (tool_integration, metadata blocks)

README updated to v6.0.0 with 100-skill count, new skill tables, and article series

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

skills/contract-review/SKILL.md

@@ -57,6 +57,14 @@ List any standard clauses absent but normally expected for this contract type.
 
 WARNING: This review is for informational purposes only and does not constitute legal advice. Always consult a qualified solicitor or lawyer before signing any legally binding agreement.
 
+## Quality Checks
+
+- [ ] Overall risk rating is justified (not just "Medium" without reasons)
+- [ ] All flagged clauses have a specific recommended action (not just "read this")
+- [ ] Missing clauses section is completed for this contract type
+- [ ] Plain English summary can be understood by a non-lawyer
+- [ ] Disclaimer is included
+
 ## Example Trigger Phrases
 - "Review this contract: [paste]"
 - "Flag the key risks in this agreement"