revert: remove unsupported defaultModel and model fields

Claude Code rejects `defaultModel` in plugin.json and `model` in agent
frontmatter with "Unrecognized key" validation error.

Removed:
- defaultModel from 6 plugin.json files
- model from 7 agent frontmatter files
- docs/MODEL-RECOMMENDATIONS.md (deleted)
- Model config sections from CONFIGURATION.md and CLAUDE.md
- Model validation from validate-marketplace.sh

This reverts Sprint 7 (v5.4.0) multi-model feature that was never
supported by Claude Code's plugin schema.

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

plugins/code-sentinel/.claude-plugin/plugin.json

@@ -2,7 +2,6 @@
   "name": "code-sentinel",
   "description": "Security scanning and code refactoring tools",
   "version": "1.0.1",
-  "defaultModel": "sonnet",
   "author": {
     "name": "Leo Miranda",
     "email": "leobmiranda@gmail.com"

plugins/code-sentinel/agents/security-reviewer.md

@@ -1,7 +1,6 @@
 ---
 name: security-reviewer
 description: Security-focused code review agent
-model: opus
 ---
 
 # Security Reviewer Agent

plugins/contract-validator/.claude-plugin/plugin.json

@@ -1,7 +1,6 @@
 {
   "name": "contract-validator",
   "version": "1.1.0",
-  "defaultModel": "sonnet",
   "description": "Cross-plugin compatibility validation and Claude.md agent verification",
   "author": {
     "name": "Leo Miranda",

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

@@ -1,7 +1,6 @@
 ---
 name: agent-check
 description: Agent definition validator for quick verification
-model: haiku
 ---
 
 # Agent Check Agent

plugins/data-platform/.claude-plugin/plugin.json

@@ -1,7 +1,6 @@
 {
   "name": "data-platform",
   "version": "1.1.0",
-  "defaultModel": "sonnet",
   "description": "Data engineering tools with pandas, PostgreSQL/PostGIS, and dbt integration",
   "author": {
     "name": "Leo Miranda",

plugins/data-platform/agents/data-analysis.md

@@ -1,7 +1,6 @@
 ---
 name: data-analysis
 description: Data analysis specialist for exploration and profiling
-model: opus
 ---
 
 # Data Analysis Agent

plugins/pr-review/.claude-plugin/plugin.json

@@ -1,7 +1,6 @@
 {
   "name": "pr-review",
   "version": "1.1.0",
-  "defaultModel": "sonnet",
   "description": "Multi-agent pull request review with confidence scoring and actionable feedback",
   "author": {
     "name": "Leo Miranda",

plugins/pr-review/agents/security-reviewer.md

@@ -1,7 +1,6 @@
 ---
 name: security-reviewer
 description: Security-focused code reviewer for PR analysis
-model: opus
 ---
 
 # Security Reviewer Agent

plugins/projman/.claude-plugin/plugin.json

@@ -1,7 +1,6 @@
 {
   "name": "projman",
   "version": "3.3.0",
-  "defaultModel": "sonnet",
   "description": "Sprint planning and project management with Gitea integration",
   "author": {
     "name": "Leo Miranda",

plugins/projman/agents/code-reviewer.md

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

plugins/projman/agents/planner.md

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

plugins/viz-platform/.claude-plugin/plugin.json

@@ -1,7 +1,6 @@
 {
   "name": "viz-platform",
   "version": "1.1.0",
-  "defaultModel": "sonnet",
   "description": "Visualization tools with Dash Mantine Components validation, Plotly charts, and theming",
   "author": {
     "name": "Leo Miranda",

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

@@ -1,7 +1,6 @@
 ---
 name: component-check
 description: DMC component validation specialist
-model: haiku
 ---
 
 # Component Check Agent