Configure flexible deployment with environment variables

- Change Flask port from 8080 to 5000 for consistency
- Add environment-based network mode configuration (bridge/host)
- Support both Windows Docker Desktop and Linux LXC deployments
- Remove obsolete docker-compose version and conflicting network settings
- Add .env.example with platform-specific configuration guidance

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

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

.env.example

@@ -0,0 +1,20 @@
+# WOL Manager Environment Configuration
+
+# Network mode configuration
+# For Windows/macOS Docker Desktop: use "bridge"
+# For Linux/LXC/Proxmox: use "host" for guaranteed WOL functionality
+WOL_NETWORK_MODE=bridge
+
+# External port mapping (only used with bridge mode)
+# For Windows/macOS: set the external port you want to access
+# For Linux with host mode: this setting is ignored
+WOL_EXTERNAL_PORT=5000
+
+# Examples:
+# Windows Docker Desktop:
+# WOL_NETWORK_MODE=bridge
+# WOL_EXTERNAL_PORT=5000
+
+# Linux LXC/Proxmox:
+# WOL_NETWORK_MODE=host
+# WOL_EXTERNAL_PORT=5000  # ignored in host mode