feat: add 5 new specialized agents with 20 skills

Add domain expert agents with comprehensive skill sets:
- service-mesh-expert (cloud-infrastructure): Istio/Linkerd patterns, mTLS, observability
- event-sourcing-architect (backend-development): CQRS, event stores, projections, sagas
- vector-database-engineer (llm-application-dev): embeddings, similarity search, hybrid search
- monorepo-architect (developer-essentials): Nx, Turborepo, Bazel, pnpm workspaces
- threat-modeling-expert (security-scanning): STRIDE, attack trees, security requirements

Update all documentation to reflect correct counts:
- 67 plugins, 99 agents, 107 skills, 71 commands

docs/agent-skills.md

@@ -1,6 +1,6 @@
 # Agent Skills
 
-Agent Skills are modular packages that extend Claude's capabilities with specialized domain knowledge, following Anthropic's [Agent Skills Specification](https://github.com/anthropics/skills/blob/main/agent_skills_spec.md). This plugin ecosystem includes **57 specialized skills** across 15 plugins, enabling progressive disclosure and efficient token usage.
+Agent Skills are modular packages that extend Claude's capabilities with specialized domain knowledge, following Anthropic's [Agent Skills Specification](https://github.com/anthropics/skills/blob/main/agent_skills_spec.md). This plugin ecosystem includes **107 specialized skills** across 18 plugins, enabling progressive disclosure and efficient token usage.
 
 ## Overview
 
@@ -187,7 +187,7 @@ fastapi-templates skill → Supplies production-ready templates
 
 ## Specification Compliance
 
-All 55 skills follow the [Agent Skills Specification](https://github.com/anthropics/skills/blob/main/agent_skills_spec.md):
+All 107 skills follow the [Agent Skills Specification](https://github.com/anthropics/skills/blob/main/agent_skills_spec.md):
 
 - ✓ Required `name` field (hyphen-case)
 - ✓ Required `description` field with "Use when" clause