Add T8501 (Eufy Solo Smart Lock D20) lock/unlock support (V12 protocol)

[dastorie]

Summary

The Eufy Solo Smart Lock D20 (T8501) is already detected as a lock and its state reads correctly, but lock/unlock commands are silently ignored. Root cause: it's routed to the legacy wifi-lock P2P protocol, but the T8501 only responds to the "V12" lock protocol (getLockV12P2PCommand, the same family as the R10/R20 retrofit locks). Routing it through V12 makes lock/unlock work. No new DeviceType/DeviceProperties entries are needed.

Closes #226.

Device facts (captured from a live unit)

Field	Value
device_type	53 (LOCK_WIFI_NO_FINGER)
device_model	T8501
serial prefix	T8501… (it is its own station)
hardwareVersion	P0
softwareVersion	1.0.4.0
Device.isLock(53)	already true
state (locked / lockStatus / battery)	reads fine

State arrives over MQTT (smart-lock message, eventType 770 lockState / 261 unlock / 264 lock), which is why state has always worked even though every command was being dropped.

Root cause

Station.lockDevice() dispatched device_type 53 via isLockWifiNoFinger() into the legacy branch (getLockP2PCommand, P2P_ON_OFF_LOCK). The "P0" hardware superficially resembles the modern smart-lock family, but neither the legacy nor the smart-lock (getSmartLockP2PCommand) protocol gets any response from this device — only getLockV12P2PCommand does.

Evidence (redacted P2P traces)

# legacy (as shipped):  no response
getLockP2PCommand cmd 1961 (P2P_ON_OFF_LOCK)          -> lock does not move
P2P_QUERY_STATUS_IN_LOCK (1955)                       -> return_code -133 (ERROR_COMMAND_TIMEOUT)

# smart-lock:  no response
getSmartLockP2PCommand cmd 6018 / handshake 6016,6012 -> no P2P response

# V12:  WORKS
getLockV12P2PCommand handshake 6016,6012              -> return_code 0 (ERROR_PPCS_SUCCESSFUL), command_type 1930
  UNLOCK -> locked=false, lockStatus 4->3, MQTT unlock event (261)
  LOCK   -> locked=true,  lockStatus 3->4, MQTT lock  event (264)

Both directions physically actuate the bolt and the state reflects back.

What changed

• src/http/device.ts — add Device.isLockWifiT8501(type, serial) (device_type 53 and serial starts with T8501, so other type-53 devices are unaffected — mirrors the existing T8510P/T8520P serial-prefix split), plus the instance wrapper.
• src/http/station.ts — route T8501 through the V12 branch in lockDevice, getLockParameters and getLockStatus; exclude it from the legacy isLockWifi()/isLockWifiNoFinger() branch. The RSA lock public key is still fetched (V12 needs it), so the public-key gate is unchanged.

Builds clean (tsc); the change follows the existing file style.

Known-incomplete (not needed for lock/unlock): calibrateLock() and a few other per-feature dispatch sites still route device_type 53 down the legacy path. Only lock/unlock + connect-time params/status were changed here; the rest can follow the same isLockWifiT8501() routing if desired.

Verification

• Library standalone: UNLOCK then LOCK both return return_code 0, the bolt physically moves, locked/lockStatus update, and MQTT lock/unlock events fire.
• End-to-end via Home Assistant (fuatakgun/eufy_security → eufy-security-ws 3.0.1 → patched client): lock.unlock / lock.lock actuate the real D20 and Home Assistant reflects the state.

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