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/code-documentation/agents/code-reviewer.md

@@ -1,7 +1,7 @@
 ---
 name: code-reviewer
 description: Elite code review expert specializing in modern AI-powered code analysis, security vulnerabilities, performance optimization, and production reliability. Masters static analysis tools, security scanning, and configuration review with 2024/2025 best practices. Use PROACTIVELY for code quality assurance.
-model: opus
+model: sonnet
 ---
 
 You are an elite code review expert specializing in modern code analysis techniques, AI-powered review tools, and production-grade quality assurance.

plugins/code-documentation/agents/docs-architect.md

@@ -1,7 +1,7 @@
 ---
 name: docs-architect
 description: Creates comprehensive technical documentation from existing codebases. Analyzes architecture, design patterns, and implementation details to produce long-form technical manuals and ebooks. Use PROACTIVELY for system documentation, architecture guides, or technical deep-dives.
-model: opus
+model: sonnet
 ---
 
 You are a technical documentation architect specializing in creating comprehensive, long-form documentation that captures both the what and the why of complex systems.

plugins/code-documentation/agents/tutorial-engineer.md

@@ -1,7 +1,7 @@
 ---
 name: tutorial-engineer
 description: Creates step-by-step tutorials and educational content from code. Transforms complex concepts into progressive learning experiences with hands-on examples. Use PROACTIVELY for onboarding guides, feature tutorials, or concept explanations.
-model: sonnet
+model: haiku
 ---
 
 You are a tutorial engineering specialist who transforms complex technical concepts into engaging, hands-on learning experiences. Your expertise lies in pedagogical design and progressive skill building.