feat: add host network mode for better localhost integration

[bihari123]

Summary

This PR updates the docker-compose.yaml to use host network mode, which significantly improves localhost integration for users running local LLM services like Ollama.

Changes

• Switched from bridge to host network mode
• Added HOSTNAME=0.0.0.0 environment variable for proper binding
• Removed port mapping (not needed with host network mode)

Problem Solved

When running Perplexica in Docker with local Ollama instances, users face connectivity issues:

• On Linux, need to use host IP addresses instead of localhost
• Connection errors when trying to use http://localhost:11434
• Complicated setup with bridge network IPs

Solution

Host network mode allows the container to use the host's network stack directly:

• localhost works seamlessly from inside the container
• No need for host.docker.internal or manual IP configuration
• Simpler setup for local LLM integrations

Testing

Tested with:

• Dual Ollama setup (GPU on port 11434, CPU on port 11435)
• Perplexica successfully connects to both via http://localhost:11434 and http://localhost:11435
• Web interface accessible at http://localhost:3000

Platform Compatibility

Note: Host network mode is Linux-specific. Windows and Mac users should continue using the default bridge network configuration with appropriate host URLs (host.docker.internal or IP addresses).

Benefits

• ✅ Simplified configuration for Linux users
• ✅ Better localhost service integration
• ✅ No complex network troubleshooting
• ✅ Maintains existing restart: unless-stopped policy