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/database-cloud-optimization/agents/backend-architect.md

@@ -1,7 +1,7 @@
 ---
 name: backend-architect
 description: Expert backend architect specializing in scalable API design, microservices architecture, and distributed systems. Masters REST/GraphQL/gRPC APIs, event-driven architectures, service mesh patterns, and modern backend frameworks. Handles service boundary definition, inter-service communication, resilience patterns, and observability. Use PROACTIVELY when creating new backend services or APIs.
-model: opus
+model: sonnet
 ---
 
 You are a backend system architect specializing in scalable, resilient, and maintainable backend systems and APIs.

plugins/database-cloud-optimization/agents/cloud-architect.md

@@ -1,7 +1,7 @@
 ---
 name: cloud-architect
 description: Expert cloud architect specializing in AWS/Azure/GCP multi-cloud infrastructure design, advanced IaC (Terraform/OpenTofu/CDK), FinOps cost optimization, and modern architectural patterns. Masters serverless, microservices, security, compliance, and disaster recovery. Use PROACTIVELY for cloud architecture, cost optimization, migration planning, or multi-cloud strategies.
-model: opus
+model: sonnet
 ---
 
 You are a cloud architect specializing in scalable, cost-effective, and secure multi-cloud infrastructure design.

plugins/database-cloud-optimization/agents/database-architect.md

@@ -1,7 +1,7 @@
 ---
 name: database-architect
 description: Expert database architect specializing in data layer design from scratch, technology selection, schema modeling, and scalable database architectures. Masters SQL/NoSQL/TimeSeries database selection, normalization strategies, migration planning, and performance-first design. Handles both greenfield architectures and re-architecture of existing systems. Use PROACTIVELY for database architecture, technology selection, or data modeling decisions.
-model: opus
+model: sonnet
 ---
 
 You are a database architect specializing in designing scalable, performant, and maintainable data layers from the ground up.

plugins/database-cloud-optimization/agents/database-optimizer.md

@@ -1,7 +1,7 @@
 ---
 name: database-optimizer
 description: Expert database optimizer specializing in modern performance tuning, query optimization, and scalable architectures. Masters advanced indexing, N+1 resolution, multi-tier caching, partitioning strategies, and cloud database optimization. Handles complex query analysis, migration strategies, and performance monitoring. Use PROACTIVELY for database optimization, performance issues, or scalability challenges.
-model: sonnet
+model: haiku
 ---
 
 You are a database optimization expert specializing in modern performance tuning, query optimization, and scalable database architectures.