[ignition-module] Gateway hook — MIRA API proxy to FastAPI backend

[Mikecranesync]

Context

Part of the automation-tie-in epic. HTTP client layer inside the Ignition gateway hook.

Task

In gateway/, add an HTTP client (OkHttp or Java's built-in) that:

• Forwards /diagnose queries to http://100.72.2.99:8765/diagnose
• Forwards /status polls to http://100.72.2.99:8765/health
• Surfaces DiagnosticResult responses as Ignition system notifications or Designer panel events

References

• SDK examples: https://github.com/inductiveautomation/ignition-sdk-examples
• Backend API: http://100.72.2.99:8765