feat: add Docker environment configuration for remote access

Fixes redirect issue where application redirects to localhost:3000
instead of server IP when accessed from remote browser.

Problem:
- Accessing http://192.168.1.190:3000 redirects to http://localhost:3000
- NEXTAUTH_URL was hardcoded to localhost in .env
- Remote users cannot access the application

Solution:
1. Create .env.docker with server-specific configuration
   - NEXTAUTH_URL="http://192.168.1.190:3000"
   - Ollama URL for container-to-container communication

2. Update docker-compose.yml:
   - Add env_file: .env.docker
   - Loads Docker-specific environment variables

3. Create .env.docker.example as template:
   - Document NEXTAUTH_URL configuration
   - Users can copy and customize for their server IP/domain

Files:
- .env.docker: Docker environment (gitignored)
- .env.docker.example: Template for users
- docker-compose.yml: Load .env.docker
- .env.example: Update NEXTAUTH_URL documentation

Usage:
On production server, edit .env.docker with your server IP:
NEXTAUTH_URL="http://YOUR_IP:3000"

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

docker-compose.yml

@@ -7,6 +7,8 @@ services:
       context: ./keep-notes
       dockerfile: Dockerfile
     container_name: memento-web
+    env_file:
+      - .env.docker
     ports:
       - "3000:3000"
     environment: