Add configurable data_key for Tessie entities and consolidate battery health sensors

[Bre77]

Motivation

• Some entity keys differ from the keys used in coordinator data, and sensors need an explicit mapping to read the correct values.
• Battery health fields are available in the vehicle state endpoint and should be created from the same vehicle sensors rather than a separate battery-only entity.

Description

• Add an optional data_key parameter to TessieBaseEntity and propagate it to TessieEntity, TessieBatteryEntity, TessieEnergyEntity, TessieEnergyHistoryEntity, and TessieWallConnectorEntity, and default data_key to key when not provided.
• Update _value and get to read from self.coordinator.data.get(self.data_key) and use data_key where appropriate.
• Extend TessieSensorEntityDescription with an optional data_key field and update several sensor descriptions to use explicit data_key values for battery/state-prefixed fields (for example charge_state_pack_current, charge_state_pack_voltage, charge_state_module_temp_*, charge_state_lifetime_energy_used, and charge_state_phantom_drain_percent).
• Consolidate battery health sensor creation: remove the separate battery-health entity usage and instead add BATTERY_DESCRIPTIONS sensors as vehicle sensors created via TessieVehicleSensorEntity using description.data_key, and update async_setup_entry accordingly.
• Update test fixture tests/components/tessie/fixtures/online.json to include the new example fields (lifetime_energy_used, module_temp_max, module_temp_min, pack_current, pack_voltage, phantom_drain_percent).

Testing

• Ran the tessie component test suite with pytest tests/components/tessie and the tests completed successfully.
• Updated fixtures were used by the tests and no regressions were reported by the automated test run.

---

Codex Task

[chatgpt-codex-connector]

💡 Codex Review

Here are some automated review suggestions for this pull request.

Reviewed commit: ce4de12547

ℹ️ About Codex in GitHub

Your team has set up Codex to review pull requests in this repo. Reviews are triggered when you

• Open a pull request for review
• Mark a draft as ready
• Comment "@codex review".

If Codex has suggestions, it will comment; otherwise it will react with 👍.

Codex can also answer questions or update the PR. Try commenting "@codex address that feedback".

[chatgpt-codex-connector]

Guard battery-health entities on available state keys

This change creates all BATTERY_DESCRIPTIONS sensors from data_coordinator without checking whether the mapped data_key exists. Because vehicle entities are seeded from last_state, keys like charge_state_pack_current/charge_state_pack_voltage/charge_state_phantom_drain_percent can be missing at setup (as reflected by the existing vehicles.json fixture), so these sensors now start as unknown and can stay that way for vehicles that never expose those fields. Previously, battery sensors were gated on available battery data, so this is a startup/availability regression.

Useful? React with 👍 / 👎.