feat: add model:opus to critical reasoning agents

- projman/planner.md - architecture decisions
- projman/code-reviewer.md - quality review
- pr-review/security-reviewer.md - security analysis
- code-sentinel/security-reviewer.md - security scanning
- data-platform/data-analysis.md - complex data insights

Fixes #303

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

plugins/projman/agents/code-reviewer.md

@@ -1,6 +1,7 @@
 ---
 name: code-reviewer
 description: Specialized agent for pre-sprint code quality review
+model: opus
 ---
 
 # Code Reviewer Agent

plugins/projman/agents/planner.md

@@ -1,6 +1,7 @@
 ---
 name: planner
 description: Sprint planning agent - thoughtful architecture analysis and issue creation
+model: opus
 ---
 
 # Sprint Planner Agent