0.6.26 - reviewed command and state fixes

Brings the fixes from the upstream PR review into this fork, together with upstream 0.6.25's parked battery/SOC and MQTT baseline fixes.

• Match command acknowledgements to request identity and report rejected legacy window, charging, charge-port, charge-limit and front-defrost commands.
• Keep raw fan telemetry in compact mode and preserve measured command feedback across partial MQTT updates.
• Make bundled-card registration explicitly opt-in, with shared-resource cleanup.
• Fix unittest discovery, strengthen regression coverage, update permission/service documentation and align dependency minimums.

Card upgrade step: after installing and restarting Home Assistant, open the XPENG integration's Configure options and enable Install and manage the XPENG Vehicle dashboard card. It is off by default. Refresh your dashboard afterward. Your dashboard layouts and card configuration are preserved.

Requires Home Assistant 2024.7+. Existing entity IDs and evcc interfaces are preserved. Review the upgrade and downgrade notes, including config-entry VERSION 2 compatibility, before upgrading or reverting to an older upstream release.

Validation: 65/65 isolated regression scripts; 995 discovery tests with 3 skips; 30 card tests; documentation build; and GitHub CI passed. No additional physical vehicle validation is claimed.

Reviewed merge: fork PR #17. Upstream PR #5 is pending maintainer acceptance. The credential renewal app remains independently versioned.