chore: consolidate and update deployment documentation

- Remove completed PRODUCTION_TODO_LIST.md
- Consolidate deployment guides: keep comprehensive PRODUCTION_DEPLOYMENT_GUIDE.md, remove redundant PRODUCTION_DEPLOYMENT.md
- Update all .env.example files to reflect current system:
  - Remove deprecated ADMIN_EMAIL/ADMIN_PASSWORD (now auto-generated)
  - Add proper documentation for all environment variables
  - Clarify that Umami config is optional (primary via Admin UI)
  - Add realistic examples for SMTP providers
  - Update ports to match actual defaults (3001)
- Update PRODUCTION_DEPLOYMENT_GUIDE.md:
  - Document auto-generated admin credentials process
  - Add Traefik configuration section
  - Update security checklist with current features
  - Fix outdated environment variables
  - Add nginx proxy configuration details

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

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

.env.example

@@ -1,26 +1,24 @@
-# Environment Configuration Template
-# Copy this file to .env and adjust values for your environment
+# PicPeak Development Environment Configuration
+# Copy this file to .env for local development
 
-# Development: Use docker-compose.dev.yml
-# Production: Use docker-compose.prod.yml with .env.production.example
+# SECURITY WARNING: This configuration is for development only!
+# For production, use .env.production.example
 
-# JWT Secret (CRITICAL for production)
-# Generate with: openssl rand -base64 32
-JWT_SECRET=dev-secret-change-in-production
+# JWT Secret (Change in production!)
+# Generate secure secret with: openssl rand -base64 32
+JWT_SECRET=dev-secret-DO-NOT-USE-IN-PRODUCTION
 
-# Application URLs
+# Application URLs (Docker Compose development setup)
 ADMIN_URL=http://localhost:3005
 FRONTEND_URL=http://localhost:3005
+BACKEND_URL=http://localhost:3001
 
-# Database Configuration
-# SQLite is used for development by default
-# For production PostgreSQL config, see .env.production.example
+# Database Configuration (SQLite for development)
 DATABASE_CLIENT=sqlite3
 DATABASE_PATH=./data/photo_sharing.db
 
-# Email Configuration
-# Development: Uses Mailhog (included in docker-compose.dev.yml)
-# Production: Configure real SMTP server
+# Email Configuration (Mailhog for development)
+# Access Mailhog UI at: http://localhost:8025
 SMTP_HOST=mailhog
 SMTP_PORT=1025
 SMTP_SECURE=false
@@ -28,7 +26,22 @@ SMTP_USER=
 SMTP_PASS=
 EMAIL_FROM=noreply@localhost
 
-# Optional: Umami Analytics
-UMAMI_URL=
-UMAMI_WEBSITE_ID=
-UMAMI_HASH_SALT=
+# Backend Port Configuration
+PORT=3001
+
+# Optional: Umami Analytics Backend Config
+# NOTE: Primary configuration through Admin UI > Settings > Analytics
+# These are fallback values for server-side tracking
+# UMAMI_URL=https://analytics.example.com
+# UMAMI_WEBSITE_ID=your-website-id
+# UMAMI_HASH_SALT=your-hash-salt
+
+# Development Features
+NODE_ENV=development
+LOG_LEVEL=debug
+
+# Admin Setup Notes:
+# 1. Run 'npm run migrate' in backend folder
+# 2. Admin credentials will be auto-generated
+# 3. Check ADMIN_CREDENTIALS.txt for login details
+# 4. Change password on first login (required)