feat(01-01): Next.js 15 project with Docker Compose dev environment

- Next.js 15 with App Router, TypeScript, Tailwind CSS (v4), ESLint
- docker-compose.yml with PostgreSQL 16, Redis 7, and app service
- Dockerfile (Node 20 alpine) for containerized development
- .env and .env.example with DATABASE_URL, DATABASE_URL_LOCAL, REDIS_URL
- src/app/page.tsx updated to render NetForge heading
- All three services start healthy with docker compose up -d

.env.example

@@ -0,0 +1,42 @@
+# =============================================================================
+# NetForge Environment Variables
+# =============================================================================
+# Copy this file to .env and fill in your values.
+# Never commit .env to version control.
+
+# =============================================================================
+# DATABASE
+# =============================================================================
+
+# Use this URL when running the app INSIDE Docker (app service connects to db service)
+DATABASE_URL=postgresql://netforge:netforge_dev@db:5432/netforge_dev
+
+# Use this URL when running Prisma commands FROM THE HOST (e.g., npx prisma db push, npx prisma studio)
+# The host connects to PostgreSQL exposed on localhost:5432
+DATABASE_URL_LOCAL=postgresql://netforge:netforge_dev@localhost:5432/netforge_dev
+
+# =============================================================================
+# REDIS
+# =============================================================================
+
+# Use when running inside Docker
+REDIS_URL=redis://redis:6379
+
+# Use when connecting from host
+REDIS_URL_LOCAL=redis://localhost:6379
+
+# =============================================================================
+# AUTHENTICATION
+# =============================================================================
+
+# Change this to a long random string in production!
+# Generate with: openssl rand -base64 32
+NEXTAUTH_SECRET=dev-secret-change-in-production
+
+NEXTAUTH_URL=http://localhost:3000
+
+# =============================================================================
+# APPLICATION
+# =============================================================================
+
+NODE_ENV=development