Add a reconciled N1MM-family live log source

[rwjblue]

Context

QSO Sidecar currently reads PoLo through LoFi or ADIF. Mainstream contest loggers expose live contact and station-state messages that can provide a lower-latency, logger-neutral source without turning Sidecar into a logger.

N1MM+ is the first target. DXLog exposes N1MM-style broadcasts, while WriteLog has a closely related UDP format that must be verified with fixtures rather than assumed compatible.

Scope

• Add a configurable, read-only UDP source for N1MM+ broadcasts.
• Parse and normalize, at minimum:
  • AppInfo
  • ContactInfo
  • contact replacement and deletion messages
  • RadioInfo
  • DynamicResults
• Feed contact changes through the existing normalized log-source and last-good-state boundaries from Persist last-good log state and formalize log-source boundaries #7.
• Define an explicit initial-baseline/replay workflow. A stream of live deltas must never be presented as a complete log unless Sidecar has a trusted baseline.
• Track source identity, logger/version, freshness, completeness, and reconciliation state.
• Compare logger-reported totals with Sidecar's independently computed totals without treating logger totals as authoritative.
• Evaluate DXLog and WriteLog compatibility using sanitized captured fixtures; isolate logger-specific differences behind adapters.
• Keep contact/radio telemetry separate from logger-emitted spot or cluster messages. Spot-derived data must follow the assistance policy in Centralize assistance policy across all live external sources #22.
• Bind/listen conservatively, document firewall and LAN-exposure implications, and never log raw QSO payloads at normal log levels.

Source lifecycle

Expose at least these distinguishable states:

• waiting for baseline
• loading/replaying baseline
• live and reconciled
• live but incomplete
• stale/degraded
• disconnected

Restart and packet-loss behavior must preserve the last-good log while making incompleteness visible.

Acceptance criteria

• N1MM+ add, replace, and delete events update normalized QSOs idempotently.
• App and radio messages expose logger identity and current operating context without affecting score.
• Startup cannot silently claim a complete log from live deltas alone.
• A documented replay, snapshot, or imported-baseline path can reach a reconciled state.
• Dynamic-results discrepancies are surfaced without overriding Sidecar scoring.
• Disconnect, restart, duplicate packet, out-of-order update, and missed-baseline behavior have deterministic tests.
• Last-good persistence survives malformed packets and source failure.
• Sanitized N1MM+ fixtures cover every supported message.
• DXLog and WriteLog compatibility is either fixture-tested or explicitly reported unsupported.
• Contact telemetry does not trigger an assisted-category warning; external spot telemetry does.
• Configuration, privacy, firewall, and logger-setup documentation is included.

References

• N1MM+ external broadcasts: https://n1mmwp.hamdocs.com/appendices/external-udp-broadcasts/
• DXLog external broadcasts: https://dxlog.net/docs/index.php?title=Additional_Information
• WriteLog UDP documentation: https://writelog.com/Downloads/writelog1281.pdf