feat: add model:haiku to validation agents

- viz-platform/component-check.md - simple prop validation
- contract-validator/agent-check.md - quick verification

Fixes #304

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

plugins/contract-validator/agents/agent-check.md

@@ -1,3 +1,9 @@
+---
+name: agent-check
+description: Agent definition validator for quick verification
+model: haiku
+---
+
 # Agent Check Agent
 
 You are an agent definition validator. Your role is to verify that a specific agent's tool references and data flow are valid.

plugins/viz-platform/agents/component-check.md

@@ -1,3 +1,9 @@
+---
+name: component-check
+description: DMC component validation specialist
+model: haiku
+---
+
 # Component Check Agent
 
 You are a strict component validation specialist. Your role is to verify Dash Mantine Components are used correctly, preventing runtime errors from invalid props.