feat(sensor): expose solar power, charge power and CT diagnostics

[AnDevX]

sysSolarPower, sysSolarEnergyDelta, sysChargePower, sysSolarCT, sysGridCT and
cfgCTConfig are already requested in the GraphQL device status query and present
in every poll response, but were never turned into entities — only their grid
equivalents were.

Adds six entities reusing the existing AndersenEvLiveSensor class unchanged:
sys_solar_power, sys_charge_power, sys_solar_energy_delta, sys_solar_ct,
sys_grid_ct, cfg_ct_config.

sysSolarPower lives in deviceStatus, not chargeStatus, so it reports
continuously rather than only during a charge session — this turns the
integration into a whole-house solar monitor with no new API calls, no new
dependencies, and no config changes.

Also resolves an open question about sysGridPower's declared unit: a kettle
test against a live A3 (~2.9kW kettle, car unplugged) showed
system_grid_power spike to ~2.9, confirming KILO_WATT is correct rather than
mislabelled watts.

Test plan

• ruff check / ruff format — clean
• pytest — 301/301 passing (updated entity-count assertions in
  test_sensor.py for the 6 new entities × 2 test devices)
• Verified against a live A3: new sensors read plausible values
  cross-checked against the Andersen app (solar 0.24 vs app's 0.2,
  grid 0.01 vs app's 0), and the kettle test above confirmed units

[Copilot]

Pull request overview

This PR exposes additional live-status fields already returned by the Andersen EV GraphQL device status poll as Home Assistant sensor entities, expanding the integration’s live monitoring to include solar/charge power and CT clamp diagnostics without adding new API calls or configuration.

Changes:

• Add live sensors for sysSolarPower, sysChargePower, and sysSolarEnergyDelta (kW/kWh) from deviceStatus.
• Add diagnostic live sensors for sysSolarCT, sysGridCT, and cfgCTConfig.
• Update sensor entity-count assertions in tests to account for the new entities across multiple devices.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 1 comment.

File	Description
custom_components/andersen_ev/sensor.py	Adds six new AndersenEvLiveSensor entities for solar/charge power and CT diagnostics; includes explanatory comments about unit differences between deviceStatus vs chargeStatus fields.
custom_components/andersen_ev/tests/test_sensor.py	Updates assertions to reflect the increased number of created sensor entities (including additional live sensors).

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