ERD diagram files and import instructions

If draw.io shows "Failed to execute 'atob' on 'Window': The string to be decoded is not correctly encoded", try these steps:

1) Use the Draw.io import dialog (preferred):
- Open https://app.diagrams.net or Draw.io Desktop
- File → Import From → Device (or File → Open From → Device)
- Select `resources/diagrams/erd_fixed.drawio`

2) If Import still errors, re-save file as UTF-8 without BOM using PowerShell (Windows):
```powershell
Get-Content .\resources\diagrams\erd.drawio | Set-Content -Encoding UTF8 .\resources\diagrams\erd_fixed_local.drawio
```

3) Alternative: open XML editor inside draw.io and paste the XML content directly:
- Arrange → Insert → Advanced → XML...
- Paste the contents of `erd_fixed.drawio` and click Apply.

4) If you still get an error, try the Draw.io Desktop app — it handles encodings more robustly.

Files in this folder:
- `erd.drawio` (original)
- `erd_fixed.drawio` (re-encoded version)
