[kkangg1]

Summary

This PR makes the integration reliable as an always-on Home Assistant polling integration, and restores compatibility with two breaking environment changes: Home Assistant 2026.7 (zeroconf import moved) and device firmware ≥ 5.1.10 (aggregate fields removed from the payload).

It is based on the optimized line I have been running in production against five devices (SPM02-class three-phase meters) for several weeks.

Fixes

• HA 2026.7: fix the zeroconf import path; without it the config flow fails to load entirely.
• Firmware ≥ 5.1.10: the firmware no longer reports Total*/Average* aggregates, so those entities silently disappeared. normalize_meter_data() now synthesizes them from per-phase X/Y/Z values (TotalActivePower, TotalReactivePower, TotalApparentPower, TotalCurrent, TotalForwardEnergy, TotalReverseEnergy, TotalEnergy{phase}, TotalEnergy, AverageVoltageLN, AverageLineCurrent). Firmware-provided values always win; a partial phase set never fabricates a total.
• Discovery: newer firmware advertises mDNS hostnames as BITUO TECHNIK-<model>-<sn> instead of EnergySensor-<model>-<sn>; the previous filter only matched energysensor and silently ignored those devices.
• Event-loop safety: HTTP calls have a 10s timeout, and settings/OTA metadata file I/O is moved off the event loop (async_add_executor_job).
• Transient failures: a single failed poll keeps the last data; entities only go unavailable after 2 consecutive failures (FAILURE_THRESHOLD), and missing values report unavailable instead of a bogus 0.
• Switch platform: capability is probed once at setup; meter-only models no longer poll a non-existent switch endpoint every cycle.
• Unload: async_unload_entry cleans up entry state; set_frequency applies to the target device or all devices.

Structure

• Blocking HTTP moved into api.py (BituoApiClient), polling into coordinator.py (DataUpdateCoordinator), pure payload logic into helpers.py with unit tests.
• Added tests/ (helpers normalization, repository privacy guard) and a CI workflow running them.
• Committed __pycache__ files removed; .gitignore added.

Notes for the maintainer

• I realize this is a large diff — it has grown while running in production. If you prefer, I can split it into focused PRs (e.g. HA 2026.7 import fix, firmware 5.1.10 synthesis, discovery filter) against the current file layout; just say the word.
• manifest.json currently points documentation/issue_tracker at my fork; happy to revert those to this repo before merge.
• python3 -m unittest discover -s tests — 7 tests pass; compileall clean.