POTACAT: add setup, status, recovery UX, and operator documentation

[rtreit]

Parent: #529

Summary

Make the POTACAT integration discoverable, diagnosable, and recoverable in QsoRipper after the compatible-producer status and replay-safety work is available.

Setup

• Describe QsoRipper's listener as WSJT-X-compatible QSO ingestion while retaining compatible configuration names.
• Provide a POTACAT recipe using Extra UDP, WSJT-X binary, loopback, and a dedicated port such as 2238.
• Explain how this coexists with POTACAT's primary logger integration.
• Detect and report bind conflicts without failing engine startup.

Status surfaces

Expose in GUI and CLI:

• Listener bound state and address.
• Last sender ID and endpoint.
• Last datagram and last successful import time.
• Last imported callsign/local ID.
• Imported, updated, duplicate, ignored, and error counters.
• Last actionable error.

Provide a safe local diagnostic based on receiving a valid heartbeat or test envelope. Do not create a fake QSO merely to test connectivity.

Recovery and reliability

• State clearly that UDP delivery is best-effort and has no end-to-end acknowledgement.
• Document replay/resend from POTACAT once stable external identity handling is present.
• Document optional append-only ADIF tail recovery only after POTACAT's file behavior is tested.
• Explain that edits and deletes do not synchronize through the baseline bridge.
• Explain that baseline multi-park/cross-program delivery is limited until the full-fidelity handoff task lands.

Deployment and security

• Keep loopback as the default.
• Document explicit LAN binding, Docker /udp publishing, and host firewall allowlisting.
• Explain that sender application IDs are spoofable and are not authentication.
• Do not expose ingestion broadly by default.

Tests and verification

• GUI/CLI status view-model tests.
• Bind-conflict and no-sender states.
• Documentation command/config verification on Windows and Linux/container examples.
• UX capture for material Avalonia changes.

Acceptance criteria

• An operator can configure and verify POTACAT delivery without guessing ports or packet formats.
• Healthy traffic is distinguishable from delivery failures.
• Reliability and feature limits are explicit.
• POTACAT absence or failure never blocks ordinary QsoRipper logging.