refactor/ migrate from OpenAI to OpenRouter integration

Major improvements to AI integration and developer experience:

## OpenRouter Migration
- Replaced @ai-sdk/openai with @openrouter/ai-sdk-provider
- Updated chat API route to use OpenRouter for access to 100+ AI models
- Changed environment variables from OPENAI_* to OPENROUTER_*
- Updated default model from gpt-5-mini to openai/gpt-5-mini
- Benefits: Users can now access multiple AI providers (OpenAI, Anthropic, etc.) through a single unified API

## Documentation Overhaul
- Expanded CLAUDE.md from 3 lines to comprehensive 225-line guide
- Added complete project structure, tech stack overview, and AI integration guidelines
- Documented all environment variables, scripts, and common tasks
- Added critical rules for AI assistants working with the codebase
- Enhanced checkpoint command with detailed step-by-step instructions

## README Updates
- Updated feature list to highlight OpenRouter integration
- Revised setup instructions for OpenRouter API key acquisition
- Updated environment variable examples and deployment configuration
- Changed all OpenAI references to OpenRouter throughout documentation

## Create Command Updates
- Bumped create-agentic-app version from 1.0.0 to 1.0.1
- Synchronized all template files with main project documentation
- Updated template env.example and package.json with OpenRouter configuration

## Dependency Updates
- Added @openrouter/ai-sdk-provider@^1.2.0
- Updated @ai-sdk/openai from ^2.0.53 to ^2.0.60
- Updated @ai-sdk/react from ^2.0.78 to ^2.0.86
- Updated ai from ^5.0.78 to ^5.0.86
- Updated better-auth from ^1.3.29 to ^1.3.34
- Updated drizzle-kit from ^0.31.5 to ^0.31.6
- Updated eslint from ^9.38.0 to ^9.39.0
- Various type definition updates

Breaking Changes:
- Projects must update environment variables from OPENAI_* to OPENROUTER_*
- API keys must be obtained from openrouter.ai instead of platform.openai.com
- Model names now follow OpenRouter format (e.g., "openai/gpt-5-mini")

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

create-agentic-app/template/package.json

@@ -1,6 +1,6 @@
 {
   "name": "agentic-coding-starter-kit",
-  "version": "0.1.0",
+  "version": "0.1.1",
   "scripts": {
     "dev": "next dev --turbopack",
     "build": "pnpm run db:migrate && next build",
@@ -15,14 +15,15 @@
     "db:reset": "drizzle-kit drop && drizzle-kit push"
   },
   "dependencies": {
-    "@ai-sdk/openai": "^2.0.53",
-    "@ai-sdk/react": "^2.0.78",
+    "@ai-sdk/openai": "^2.0.60",
+    "@ai-sdk/react": "^2.0.86",
+    "@openrouter/ai-sdk-provider": "^1.2.0",
     "@radix-ui/react-avatar": "^1.1.10",
     "@radix-ui/react-dialog": "^1.1.15",
     "@radix-ui/react-dropdown-menu": "^2.1.16",
     "@radix-ui/react-slot": "^1.2.3",
-    "ai": "^5.0.78",
-    "better-auth": "^1.3.29",
+    "ai": "^5.0.86",
+    "better-auth": "^1.3.34",
     "class-variance-authority": "^0.7.1",
     "clsx": "^2.1.1",
     "drizzle-orm": "^0.44.7",
@@ -40,12 +41,12 @@
   "devDependencies": {
     "@eslint/eslintrc": "^3.3.1",
     "@tailwindcss/postcss": "^4.1.16",
-    "@types/node": "^20.19.23",
-    "@types/pg": "^8.15.5",
+    "@types/node": "^20.19.24",
+    "@types/pg": "^8.15.6",
     "@types/react": "^19.2.2",
     "@types/react-dom": "^19.2.2",
-    "drizzle-kit": "^0.31.5",
-    "eslint": "^9.38.0",
+    "drizzle-kit": "^0.31.6",
+    "eslint": "^9.39.0",
     "eslint-config-next": "15.4.6",
     "shadcn": "^3.5.0",
     "tailwindcss": "^4.1.16",