feat(matter): add SBMD thermostat driver with optional fan control

[tleacmcsa]

Add Matter Thermostat device type (0x0301) support via SBMD spec with:

• Thermostat cluster (0x0201) read/write mappers for temperature setpoints, system mode, and control sequence
• Optional Fan Control cluster (0x0202) resources (fanMode, fanOn) gated by prerequisite presence checks
• Fix readableAttributeLookup to use unordered_multimap so multiple resources can read from the same cluster attribute

Testing:

• ThermostatDevice.js virtual device with side-band operations
• ThermostatWithFanDevice.js subclass adding Fan Control cluster
• Python fixtures (MatterThermostat, MatterThermostatWithFan)
• Integration tests for commission, read, write, and sideband updates
• Fan-specific tests for fanMode and fanOn resource reads

Refs: BARTON-376

[tleacmcsa]

@copilot review this PR

[Copilot]

@copilot review this PR

Review complete. Four issues were found and fixed in 86c2e9b:

MatterDevice.cpp — OnAttributeChanged

• The cache == nullptr guard was inside the per-binding loop and caused an early return (aborting all remaining bindings) even when only one binding's Get() failed. The null-cache check is now lifted before the loop, and the per-binding Get() failure uses continue so the other bindings still run.

thermostat.sbmd — dead code

• var schema = { value: {tag: null, type: 'int16'} }; in the heatSetpoint write script was defined but never referenced. Removed.

thermostat.sbmd — missing null guards

• The read scripts for absoluteMinHeatLimit, absoluteMaxHeatLimit, absoluteMinCoolLimit, absoluteMaxCoolLimit, and controlSequenceOfOperation called value.toString() without first checking for null (unlike localTemperature, heatSetpoint, and coolSetpoint which all guard). Null checks added to match the existing pattern.

matter_thermostat.py / matter_thermostat_with_fan.py — fragile internal-state override

• MatterThermostatWithFan was assigning self._matterjs_entry_point directly after super().__init__(), reaching into internal state. Added a matterjs_entry_point parameter to MatterThermostat.__init__ so the subclass can pass "ThermostatWithFanDevice.js" cleanly via the constructor chain.