Add interactive circuit connection canvas

[meozigoon]

Summary

• implement a connection canvas on the main form with four inputs and four outputs that support drag-to-connect wiring and connection previews
• extend the Logic class to manage up to four input and output connection types and expose connection metadata compatible with the UI

Testing

• dotnet build (fails: dotnet command not available in container)

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https://chatgpt.com/codex/tasks/task_e_68dba6f4d554832aa78db009d5f6ed9e