chore: upgrade Next.js 15.4.6 to 16.0.3 with full stack updates

Successfully upgraded the project from Next.js 15 to Next.js 16 stable release
with all related dependencies and configuration updates.

## Package Upgrades
- Next.js: 15.4.6 → 16.0.3
- React: 19.1.0 → 19.2.0
- React DOM: 19.1.0 → 19.2.0
- @types/react: 19.2.2 → 19.2.5
- @types/react-dom: 19.2.2 → 19.2.3
- eslint-config-next: 15.4.6 → 16.0.3

## Configuration Changes
- Removed --turbopack flag from dev script (now default in Next.js 16)
- Updated lint script from 'next lint' to 'eslint .' for better compatibility
- Migrated ESLint config from FlatCompat to native flat config format
- Removed @eslint/eslintrc dependency (no longer needed)
- Added pnpm overrides for React type definitions

## ESLint Configuration
- Converted from FlatCompat compatibility layer to direct import
- Now using eslint-config-next/core-web-vitals directly
- Added ignores for .next, node_modules, .cache, dist, and build directories
- Simplified configuration structure for better maintainability

## TypeScript Configuration
- Auto-updated by Next.js 16 build process
- Changed jsx from 'preserve' to 'react-jsx' (React automatic runtime)
- Added '.next/dev/types/**/*.ts' to include paths

## MCP Configuration
- Removed unused context7 MCP server configuration
- Updated next-devtools command to use direct npx instead of cmd wrapper

## Verification
- Build: ✅ Successful (compiled in 2.8s with Turbopack)
- Lint: ✅ No errors or warnings
- TypeScript: ✅ Type checking passed
- Browser: ✅ App loads and runs correctly

This upgrade brings all the latest Next.js 16 features and improvements
including Turbopack as the default bundler, improved build performance,
and enhanced developer experience.

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

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

create-agentic-app/template/eslint.config.mjs

@@ -1,16 +1,10 @@
-import { dirname } from "path";
-import { fileURLToPath } from "url";
-import { FlatCompat } from "@eslint/eslintrc";
+import nextConfig from "eslint-config-next/core-web-vitals";
 
-const __filename = fileURLToPath(import.meta.url);
-const __dirname = dirname(__filename);
-
-const compat = new FlatCompat({
-  baseDirectory: __dirname,
-});
-
-const eslintConfig = [
-  ...compat.extends("next/core-web-vitals", "next/typescript"),
+const config = [
+  {
+    ignores: [".next/**", "node_modules/**", ".cache/**", "dist/**", "build/**"],
+  },
+  ...nextConfig,
 ];
 
-export default eslintConfig;
+export default config;