Add README screenshots and example graph files for demo project

[Copilot]

The README lacked any visual documentation of the application — no screenshots, no example graphs, and outdated dependency information.

Changes

Example graph files (examples/)

• examples/signal-processing.json — multi-tab graph named "Signal Processing Pipeline" v2.1.0 with a Generator tab (Number Producer → Arithmetic Transform → Reporter) and a Filter tab (Pass Filter nodes for low/high-pass routing)
• examples/math-computation.json — single-tab graph named "Math Computation Demo" v1.0.0 showing parallel arithmetic (Add + Multiply) from shared inputs

Both files use the full multi-tab GraphData format with top-level name and version fields, e.g.:

{
  "name": "Signal Processing Pipeline",
  "version": "2.1.0",
  "tabs": [...]
}

Screenshots (docs/screenshots/)

• light-mode.png — captured from the running app using Xvfb + X11 software rendering

README (README.md)

• Screenshots, feature list, and dependency versions need to be updated to reflect current state (ribbon toolbar, tabs, undo/redo, node types, dark/light theme support)

Note: Dark-mode screenshot and README prose update were not completed in this session. The example graph files and light-mode screenshot are ready; the README wiring and dark-mode image still need to be added.

Warning

Firewall rules blocked me from connecting to one or more addresses (expand for details)

I tried to connect to the following addresses, but was blocked by firewall rules:

• av-build-tel-api-v1.avaloniaui.net
  • Triggering command: /usr/share/dotnet/dotnet dotnet exec --runtimeconfig /home/REDACTED/.nuget/packages/avalonia.buildservices/11.3.2/tools/netstandard2.0/runtimeconfig.json /home/REDACTED/.nuget/packages/avalonia.buildservices/11.3.2/tools/netstandard2.0/Avalonia.BuildServices.Collector.dll (dns block)
  • Triggering command: /usr/share/dotnet/dotnet dotnet exec --runtimeconfig /home/REDACTED/.nuget/packages/avalonia.buildservices/11.3.2/tools/netstandard2.0/runtimeconfig.json /home/REDACTED/.nuget/packages/avalonia.buildservices/11.3.2/tools/netstandard2.0/Avalonia.BuildServices.Collector.dll 2.58.0+dfsg-1build1_amd64.deb ame t[bot] (dns block)
  • Triggering command: /usr/share/dotnet/dotnet dotnet exec --runtimeconfig /home/REDACTED/.nuget/packages/avalonia.buildservices/11.3.2/tools/netstandard2.0/runtimeconfig.json /home/REDACTED/.nuget/packages/avalonia.buildservices/11.3.2/tools/netstandard2.0/Avalonia.BuildServices.Collector.dll nnotation=ptype=crashpad-handler /REDACTED/.config/google-chrome/Crash Reports ients2.google.com/cr/report nnel= -release=Ubuntu -rf t=Linux d=Chrome_Linux =145�� race connection inst (dns block)

If you need me to access, download, or install something from one of these locations, you can either:

• Configure Actions setup steps to set up my environment, which run before the firewall is enabled
• Add the appropriate URLs or hosts to the custom allowlist in this repository's Copilot coding agent settings (admins only)

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