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/employee-engagement-survey/SKILL.md

@@ -80,6 +80,14 @@ eNPS: Below 0 = Concerning / 0-30 = Good / 30-70 = Great / 70+ = Excellent
 
 **5. Communication Template** — Draft message to share results with employees.
 
+## Quality Checks
+
+- [ ] Survey includes anonymity statement at the start
+- [ ] eNPS question (0-10 recommend scale) is included in all survey types
+- [ ] Open-ended questions are included (not just Likert scales)
+- [ ] Analysis includes a specific action planning template (not just observations)
+- [ ] Results communication template commits to sharing back with employees by a specific date
+
 ## Example Trigger Phrases
 - "Create an employee engagement survey for our team"
 - "Design a pulse survey for [topic]"