NetVisor: patch systemd file to fix new OIDC config

[vhsdream]

✍️ Description

• v0.11x changed the way OIDC is configured. It now uses an oidc.toml file in /opt/netvisor and the server checks for it at ../oidc.toml which is hard-coded. Adding the WorkingDirectory key to the systemd service file allows the server to find the file.
• Users who have configured OIDC clients via the env file need to manually redo their config.
• Also added a new NETVISOR_CLIENT_IP_SOURCE env var (optional) if users want to ensure that the correct IP address is logged for auth when behind a reverse proxy.

🔗 Related PR / Issue

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✅ Prerequisites (X in brackets)

• Self-review completed – Code follows project standards.
• Tested thoroughly – Changes work as expected.
• No security risks – No hardcoded secrets, unnecessary privilege escalations, or permission issues.

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🛠️ Type of Change (X in brackets)

• 🐞 Bug fix – Resolves an issue without breaking functionality.
• ✨ New feature – Adds new, non-breaking functionality.
• 💥 Breaking change – Alters existing functionality in a way that may require updates.
• 🆕 New script – A fully functional and tested script or script set.
• 🌍 Website update – Changes to website-related JSON files or metadata.
• 🔧 Refactoring / Code Cleanup – Improves readability or maintainability without changing functionality.
• 📝 Documentation update – Changes to README, AppName.md, CONTRIBUTING.md, or other docs.