Matter: add Electrical Power Measurement cluster to On/Off Plug-in Unit

[lboue]

Description:

Adds Matter support for live electrical power reporting on relay/plug endpoints:

• New relay_power plugin (Matter_Plugin_OnOff_Power, Matter_Plugin_3_OnOff_Power.be): extends the existing relay On/Off Plug-in Unit (device type 0x010A) with the Electrical Power Measurement cluster (0x0090, Matter 1.4.1 §2.13). Reads Voltage/Current/Power/ApparentPower/ReactivePower/Factor/Frequency from Tasmota's ENERGY sensor JSON (single-channel energy monitoring chips: HLW8012, BL0937, CSE7766, ADE7953, PZEM, ...) and exposes them as RMSVoltage, RMSCurrent, ActivePower, RMSPower, ApparentPower, ReactivePower, Frequency, PowerFactor, plus the mandatory PowerMode/NumberOfMeasurementTypes/Accuracy attributes. This lets Matter controllers (Apple Home, Google Home, SmartThings, ...) display live power usage for Tasmota smart plugs, the same way many commercial Matter plugs do.
• New v_relay_power virtual variant (Matter_Plugin_Virt_OnOff_Power, Matter_Plugin_9_Virt_OnOff_Power.be): lets the cluster be exercised without physical hardware, driven entirely through the MtrUpdate command (e.g. MtrUpdate {"Name":"Plug","Voltage":230.5,"Current":0.42,"ActivePower":95.6}). Useful for testing/demoing without an energy-monitoring device.
• New http_relay_power bridge variant (Matter_Plugin_Bridge_OnOff_Power, Matter_Plugin_8_Bridge_OnOff_Power.be): same cluster, but polling a remote Tasmota device over HTTP (Status 10) instead of local sensors, completing the local/virtual/bridge trio already used by other plugins.
• Matter_Plugin_0.be: registers FEATURE_MAPS/CLUSTER_REVISIONS entries for cluster 0x0090.
• Matter_UI.be:
  • adds relay_power, v_relay_power and http_relay_power to the endpoint-type configuration dropdowns.
  • improves the "Add Remote sensor or device" auto-detection: when the probed remote device reports an ENERGY sensor, the first detected relay is now suggested as relay_power instead of plain light0/relay (the type is otherwise not editable for already-detected rows, so without this the cluster was unreachable from that screen). Only the first relay is tagged, since most Tasmota energy-monitoring boards (single CSE7766/HLW8012/etc. chip) have one shared meter for the whole device rather than one per relay — tagging every relay would duplicate the same aggregate reading misleadingly.
• be_matter_module.c: registers the new solidified plugin headers (this file maintains an explicit include list with no auto-discovery; the initial push was missing the first pair and failed CI, fixed in a follow-up commit).

Design notes:

• The cluster is added directly on the existing "On/Off Plug-in Unit" endpoint rather than composed as a separate "Electrical Sensor" (0x0510) device type, matching common real-world Matter plug implementations.
• Single measurement channel only; multi-phase/multi-channel energy (Voltage1/2, Power1/2, ...) is out of scope for this PR.
• Electrical Energy Measurement (0x0091, cumulative kWh) is not covered by this PR.
• In the virtual variant, the wattage test key is ActivePower rather than Power, since Power is already the inherited On/Off boolean command.

Related issue (if applicable): N/A

Test results:

Flashed and tested on real hardware: ESP32-S3 (tasmota32s3 env), Tasmota 15.5.0.2(tasmota32), Core 3.3.8.

Local + virtual (relay_power / v_relay_power)

• Built and flashed via PlatformIO (pio run -e tasmota32s3 --target upload) — build succeeds (Flash 70.7%, RAM 21.9%).
• Configured endpoint 2 as v_relay_power via the Matter web UI; commissioned the device with chip-tool (manual pairing code) onto a test fabric — commissioning completed successfully.
• chip-tool descriptor read device-type-list confirms endpoint 2 reports device type 266 (On/Off Plug-in Unit) alongside 19 (Bridged Node).
• Read the ElectricalPowerMeasurement cluster (0x0090) on endpoint 2 via chip-tool:
  • PowerMode = 2 (AC), NumberOfMeasurementTypes = 8.
  • Accuracy: 8 MeasurementAccuracyStruct entries returned with correct MeasurementType enums, min/max ranges and AccuracyRanges — matches the declarative table in the plugin.
  • Before any update, ActivePower/ReactivePower/ApparentPower/Frequency/PowerFactor correctly read back null (nullable/X quality, as specified).
• Sent MtrUpdate {"Ep":2,"Power":1,"Voltage":230.5,"Current":0.42,"ActivePower":95.6,"ApparentPower":98.1,"ReactivePower":12.0,"Factor":0.97,"Frequency":50.0} via the console — accepted (RESULT = {"MtrUpdate":{"Ep":2,"Power":1}}).
• Re-read via chip-tool after the update:
  • ActivePower = 95600 (mW) ✓ matches 95.6 W × 1000.
  • RMSVoltage = 230500 (mV) ✓ matches 230.5 V × 1000.
• Serial console confirmed no crash/exception around commissioning or the virtual update (Status 0 reports healthy heap ~190KB free, stable uptime, Wifi connected throughout).

Bridge (http_relay_power) against a real remote device

• Bridged a real NOUS A5T 4-outlet power strip (single shared CSE7766 meter, ENERGY in its Status 10) at a separate IP on the LAN.
• Before the auto-detect fix: all 4 relays were suggested (and had been added) as http_light0 ("Light 0 OnOff") — the shared power meter was invisible from Matter, and the type wasn't editable for already-probed rows.
• After the fix: re-probing via "Add Remote Tasmota or OpenBK" now returns [{"relay":1,"type":"http_relay_power"},{"relay":2,"type":"http_light0"},{"relay":3,"type":"http_light0"},{"relay":4,"type":"http_light0"}] — only relay 1 is tagged with the power cluster.
• Deleted the old relay-1 http_light0 endpoint, re-ran the probe, added the new http_relay_power endpoint for relay 1 — the existing relay 2/3/4 endpoints were correctly recognized as duplicates and skipped (no double endpoints).
• Tasmota's own status list now shows Power1 Off 2.0W (bridge-polled ActivePower displayed next to the On/Off state via web_values()) while Power2/Power3/Power4 remain plain on/off — matching the physical reality of one shared meter across four sockets.

Not yet tested: ESP8266 build, and the physical (non-virtual, non-bridge) relay_power path against a locally-attached energy-monitoring chip.

Checklist:

• The pull request is done against the latest development branch
• Only relevant files were touched
• Only one feature/fix was added per PR and the code change compiles without warnings
• The code change is tested and works with Tasmota core ESP8266 V.2.7.8
• The code change is tested and works with Tasmota core ESP32 V.3.3.8 from Platform 2026.05.50
• I accept the CLA.

NOTE: The code change must pass CI tests. Your PR cannot be merged unless tests pass