feat: v10.0.0 — 8 new skills across Customer Success and Engineering (500-star milestone)

Two star milestones shipped together:

Customer Success bundle (pm-cs) — 250-star milestone:
- cs-health-scorecard: weighted RAG health score across 5 dimensions with renewal forecast
- qbr-deck: slide-by-slide QBR structure with value narrative and mutual commitments
- cs-escalation-brief: 4-level escalation framework with root cause, impact, and decision required
- churn-analysis: voluntary/unavoidable churn split, early warning signals, prioritised interventions

Engineering expansion (pm-engineering) — 500-star milestone:
- cicd-playbook: full pipeline playbook from build through post-deploy checks and rollback
- slo-error-budget: SLI definitions, burn rate alerts, and error budget policy
- developer-onboarding-doc: first-week guide covering architecture, setup, testing, and contacts
- oncall-runbook: per-alert response procedures, escalation matrix, and handoff template

Also:
- Added pm-cs plugin to marketplace.json
- Updated pm-engineering plugin.json to v3.0.0 (14 skills)
- Updated marketplace.json to v10.0.0 (114 skills, 23 bundles, 16 professions)
- README updated with new CS section, corrected skill numbering (106 → 114)
- Added bug report link to Contributing section
- Star milestones updated to show 250 and 500 as unlocked

.claude-plugin/marketplace.json

@@ -1,8 +1,8 @@
 {
   "$schema": "https://anthropic.com/claude-code/marketplace.schema.json",
   "name": "pm-claude-skills",
-  "version": "9.0.0",
-  "description": "106 Claude Skills + 4 templates across 22 plugin bundles plus the first agent template (PM Sprint Agent), covering 15 professions — product management, engineering, legal, finance, HR, sales, design, Figma, marketing, and more. Building blocks for the Anthropic agent template architecture.",
+  "version": "10.0.0",
+  "description": "114 Claude Skills + 4 agent templates across 23 plugin bundles covering 16 professions — product management, engineering, customer success, legal, finance, HR, sales, design, Figma, marketing, and more. Building blocks for the Anthropic agent template architecture.",
   "owner": {
     "name": "Mohit Aggarwal",
     "email": "mohit15856@gmail.com"
@@ -82,12 +82,20 @@
     },
     {
       "name": "pm-engineering",
-      "description": "Engineering & tech skills: Code Review Checklist, Incident Postmortem, API Docs Writer, Architecture Decision Record, Debugging Log Analyser, PR Description Writer, System Design Interview, Changelog Generator, Test Strategy Doc, Runbook Writer. 10 structured skills for engineering teams, SREs, and technical PMs.",
-      "version": "2.0.0",
+      "description": "Engineering & tech skills: Code Review Checklist, Incident Postmortem, API Docs Writer, Architecture Decision Record, Debugging Log Analyser, PR Description Writer, System Design Interview, Changelog Generator, Test Strategy Doc, Runbook Writer, CI/CD Playbook, SLO & Error Budget, Developer Onboarding Doc, On-Call Runbook. 14 structured skills for engineering teams, SREs, and technical PMs.",
+      "version": "3.0.0",
       "category": "productivity",
       "source": "./plugins/pm-engineering",
       "homepage": "https://github.com/mohitagw15856/pm-claude-skills"
     },
+    {
+      "name": "pm-cs",
+      "description": "Customer Success skills: Customer Health Scorecard, QBR Deck, Escalation Brief, Churn Analysis. Score account health with a weighted RAG framework, build structured QBR decks with value narratives, write crisp escalation briefs for at-risk accounts, and analyse churn by category and segment with prioritised interventions.",
+      "version": "1.0.0",
+      "category": "productivity",
+      "source": "./plugins/pm-cs",
+      "homepage": "https://github.com/mohitagw15856/pm-claude-skills"
+    },
     {
       "name": "pm-data",
       "description": "Data & analytics skills: Metrics Framework, SQL Query Explainer, Dashboard Brief, Chart Data Extractor. Build North Star metric trees, explain SQL, spec dashboards, and digitise chart images.",