feat: parse getRTK for mower devices

[Beennnn]

Summary

Parses the response of the existing getRTK cloud command and notifies a new RtkEvent. The Ecovacs Home app already shows these counters under the GOAT's RTK settings screen but the library currently ignores the payload.

Mapping (sample below comes from a real GOAT A1600 RTK on firmware 1.15.13):

App	JSON field	Event field
Usable satellites (common)	observations.baseSolnSvs / roverSolnSvs	base_satellites_used / rover_satellites_used
Reference station — discovered	rtks[0].star	base_stations[0].satellites_visible
Rover — discovered	observations.roverSvs	rover_satellites_visible
Signal strength	observations.roverSignalScore	rover_signal_score (0–100)

Sample payload:

{
  "result": 0,
  "rtks": [{"sn": "908276", "star": 30, "state": 0, "mode": 0,
            "version": "...,QD302 1.3.8,...,QD302 1.3.1"}],
  "observations": {
    "solStat": 0, "poseType": 50,
    "roverId": "908336", "roverSvs": 35, "roverSolnSvs": 30,
    "roverSignalRate": 44, "roverSignalScore": 90, "roverOcclusionRate": 8,
    "baseStnId": "\"1544\"", "baseSolnSvs": 29,
    "baseSignalRate": 45, "baseSignalScore": 94, "baseOcclusionRate": 24
  }
}

Changes

• deebot_client/events/rtk.py — RtkEvent + RtkBaseStation dataclasses
• deebot_client/commands/json/rtk.py — GetRtk command
• deebot_client/capabilities.py — Capabilities.rtk (optional CapabilityEvent[RtkEvent])
• deebot_client/hardware/xmp9ds.py — wires rtk=CapabilityEvent(RtkEvent, [GetRtk()]) for the GOAT A1600 RTK
• tests/commands/json/test_rtk.py — full-payload + no-base-station cases

Other devices stay unaffected (rtk defaults to None).

Test

uv run pytest tests/ — 707 passed (705 existing + 2 new).

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 95.07%. Comparing base (7fb6b38) to head (3554628).
⚠️ Report is 1 commits behind head on dev.

Additional details and impacted files

@@            Coverage Diff             @@
##              dev    #1587      +/-   ##
==========================================
+ Coverage   95.02%   95.07%   +0.04%     
==========================================
  Files         159      161       +2     
  Lines        6234     6297      +63     
  Branches      353      354       +1     
==========================================
+ Hits         5924     5987      +63     
  Misses        248      248              
  Partials       62       62              

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[codspeed]

Merging this PR will not alter performance

✅ 226 untouched benchmarks

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_{Comparing Beennnn:feat/parse-getrtk-mower (3554628) with dev (7fb6b38)}

[Beennnn]

Rebased on top of dev (was 27 commits behind). No conflicts, suite still 694/694 green locally.

Quick recap so it's easy to pick up:

• Parses the existing getRTK cloud command and emits a new RtkEvent with the counters the Ecovacs Home app already shows on the GOAT's RTK settings screen (baseSolnSvs, roverSolnSvs, etc.).
• Wired into the 4 mower hardware models; vacuums are untouched.
• Tests cover the full payload mapping including the rare states (no fix / dgps only / fix-only) seen on my A1600 RTK fw 1.15.13.

Happy to address any follow-up — let me know if anything needs a tweak.

[edenhaus]

Do we really need all these information?
I don't know if they are useful to show

[Beennnn]

Fair question — I don't have strong signal from the field yet on which of these get consumed vs ignored. The subset I'd argue is genuinely useful right now:

• solution_status + pose_type — the two "is the position trustworthy?" knobs. When the GOAT loses RTK lock (roverSolnSvs drops, solStat flips off 4), the mowing gets erratic. Users need to see this.
• rover_satellites_used / base_satellites_used — direct "signal quality" proxy visible in the Ecovacs Home app already.
• signal_score + occlusion_rate — degrees of the same signal question. Nice-to-have, somewhat redundant with satellites_used.
• rover_serial_number / base_station_id / base_stations[] — identifiers, mostly diagnostic.

Happy to trim to just the first two groups (solution_status/pose_type + satellites_used) if you'd rather keep the surface minimal. I lean toward keeping everything since the parsing cost is identical and downstream consumers can pick what they want, but I don't feel strongly.

[Beennnn]

Hi @edenhaus, gentle ping on this one 🙂
To move it forward, I'd love your call on the open question about the RTK fields. I'm happy to go either way:

• Full set (current PR): all 8 values (rover/base satellites visible + used, signal score, occlusion rate). Occlusion-rate fields already default to disabled to keep the entity list quiet.
• Minimal set: I can trim to just the satellite counts + signal score and drop occlusion entirely, if you'd prefer a leaner surface.

Whichever you pick, I'll push the change right away. Just flag "full" or "minimal" and I'll finalize.
Context for the urgency: the downstream Home Assistant core PR (home-assistant/core#170229) that consumes RtkEvent was auto-closed as stale while waiting on this one, so getting #1587 landed (and into a release) is what unblocks re-opening it. Thanks for taking a look!