1.4.0rc1 — opt-in fast cloud power updates

This experimental prerelease implements the native burst polling requested in
#69, separately from the 1.3.1 maintenance candidate. It includes RC3's charger
connection guard. Neither release line is promoted to stable by this release.

Enable and test

Enable beta versions in HACS, select v1.4.0rc1 and restart Home Assistant. In the
integration's options, enable Enable fast cloud power updates (experimental).
It is disabled by default. The normal update interval still governs all other
cloud readings. Burst cadence follows the device/server delay; two-second updates
are not promised for every device or account.

• Station PV Power and hybrid EV Charger Power use the independent fast loop.
• Single-inverter PV channel power keeps its existing entity IDs.
• Each microinverter with a known serial gains AC Power. Multi-inverter stations
  gain explicitly addressed per-inverter PV port power sensors.
• Disconnected/stale samples are unavailable; genuine connected zero remains zero.
• Station and inverter errors back off independently. Ordinary PV data can take
  over on transport failure, with automatic recovery to burst. Explicit offline
  streams do not resurrect cached slow power.
• Energy counters, grid/load/battery semantics and device controls are unchanged.

Disabling the option stops burst polling and returns existing sensors to their
ordinary sources. Burst-only entities then become unavailable. Back up before
installing; restore RC3 and restart to roll back. RC2/RC3 tags remain unchanged.

Evidence and limits

See protocol and validation notes
for pinned comparisons with ioBroker, the MS-A2 MQTT client and Homebridge.

172 standalone regression tests pass. Home Assistant 2026.9.2 lifecycle tests with 15
simulated stations covers option-off/on behavior, routing, scheduling, competing
slow updates, failures and unload, plus options and isolated two-account storage reloads. A bounded read-only real hybrid probe returned
three connected samples at a 10-second cadence with advancing timestamps and
usable PV power through the new poller. No device command was sent.

HMS power/mis mapping is source-validated and tested with synthetic payloads;
real HMS and multi-inverter comparisons remain outstanding. The configured live
account did not supply a microinverter scope. EU installer/web endpoints only;
consumer-specific MS-A2 endpoints and additional regions remain unsupported here.
Missing voltage/current/temperature fields are not invented or made faster.

Issue #69 remains open pending hardware testing. The separate #71/#72 triage and
1.3.1 stable-promotion gates also remain documented in the RC3 release notes.