fix: merge last_service_data across split calls to fix detect_non_ha_changes with separate_turn_on_commands

[roeehendel]

Bug

separate_turn_on_commands: true causes each adaptation cycle to make two sequential light.turn_on calls — one for brightness, one for color. Each call overwrote last_service_data, so after the color call, brightness was gone.

When detect_non_ha_changes: true checks for manual changes, _attributes_have_changed reads brightness from last_service_data. With brightness absent, the comparison is silently skipped — so brightness changes made directly on the bulb (e.g. via a Zigbee-bound switch bypassing HA) were never detected, and AL kept overriding them.

Fix

Merge into last_service_data instead of overwriting, so attributes accumulate across split calls:

self.manager.last_service_data[light] = {
    **self.manager.last_service_data.get(light, {}),
    **service_data,
}

reset() clears last_service_data when a light turns off, so there is no stale-data concern.

Testing

Added test_detect_non_ha_changes_with_separate_turn_on_commands in tests/test_switch.py, which:

1. Force-adapts and asserts last_service_data contains both brightness and color_temp_kelvin after the split calls
2. Simulates a direct Zigbee brightness change
3. Asserts the light is marked manually_controlled=BRIGHTNESS on the next interval
4. Asserts AL does not override the manual brightness on the following interval

Live-tested on HAOS 17.0 / HA Core 2026.2.1 with an IKEA TRADFRI bulb + RODRET switch. Before the fix, AL overrode manual brightness every interval. After the fix, the manual change is detected and respected.

[roeehendel]

Ping, let me know if you have any feedback or need changes.

[homeassilol]

Good catch — the overwrite bug is real and the test proves it. One minor suggestion: consider using dict.update() instead of {**existing, **new} to avoid allocating a new dict on each call:

existing = self.manager.last_service_data.setdefault(light, {})
existing.update(service_data)

Otherwise LGTM — well tested with live verification on HAOS.