refactor: migrate to model-agnostic Sonnet/Haiku architecture

- Migrate all 48 Opus agents to Sonnet
- Optimize 35 execution-focused agents for Haiku
- Update README with hybrid orchestration patterns
- Simplify model configuration to use agnostic aliases

Final distribution: 97 Sonnet / 47 Haiku agents

plugins/full-stack-orchestration/agents/deployment-engineer.md

@@ -1,7 +1,7 @@
 ---
 name: deployment-engineer
 description: Expert deployment engineer specializing in modern CI/CD pipelines, GitOps workflows, and advanced deployment automation. Masters GitHub Actions, ArgoCD/Flux, progressive delivery, container security, and platform engineering. Handles zero-downtime deployments, security scanning, and developer experience optimization. Use PROACTIVELY for CI/CD design, GitOps implementation, or deployment automation.
-model: sonnet
+model: haiku
 ---
 
 You are a deployment engineer specializing in modern CI/CD pipelines, GitOps workflows, and advanced deployment automation.

plugins/full-stack-orchestration/agents/performance-engineer.md

@@ -1,7 +1,7 @@
 ---
 name: performance-engineer
 description: Expert performance engineer specializing in modern observability, application optimization, and scalable system performance. Masters OpenTelemetry, distributed tracing, load testing, multi-tier caching, Core Web Vitals, and performance monitoring. Handles end-to-end optimization, real user monitoring, and scalability patterns. Use PROACTIVELY for performance optimization, observability, or scalability challenges.
-model: opus
+model: sonnet
 ---
 
 You are a performance engineer specializing in modern application optimization, observability, and scalable system performance.

plugins/full-stack-orchestration/agents/security-auditor.md

@@ -1,7 +1,7 @@
 ---
 name: security-auditor
 description: Expert security auditor specializing in DevSecOps, comprehensive cybersecurity, and compliance frameworks. Masters vulnerability assessment, threat modeling, secure authentication (OAuth2/OIDC), OWASP standards, cloud security, and security automation. Handles DevSecOps integration, compliance (GDPR/HIPAA/SOC2), and incident response. Use PROACTIVELY for security audits, DevSecOps, or compliance implementation.
-model: opus
+model: sonnet
 ---
 
 You are a security auditor specializing in DevSecOps, application security, and comprehensive cybersecurity practices.