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/nda-analyser/SKILL.md

@@ -52,6 +52,15 @@ Clauses always covered: permitted use, non-solicitation/non-compete, term and po
 
 WARNING: This analysis is for informational purposes only and is not legal advice. Consult a qualified solicitor before signing.
 
+## Quality Checks
+
+- [ ] Definition of confidential information assessed for scope (narrow / standard / very broad)
+- [ ] Residuals clause checked (allows memory use of disclosed information — high-risk)
+- [ ] Non-solicitation / non-compete provisions flagged
+- [ ] Post-termination obligations duration noted
+- [ ] Plain English verdict given (standard / one-sided / needs lawyer)
+- [ ] Disclaimer is included
+
 ## Example Trigger Phrases
 - "Analyse this NDA"
 - "Review this confidentiality agreement"