Split low power charge at dawn, bug fixes

What's Changed

### Features

• fix(plan): split low-power charge windows at dawn, not window end by @chalfontchubby in #4577

Cloud inverter fixes

• fix(sunsynk): make the settings write actually work — group, Sell flag, encodings by @springfall2008 in #4589
• fix(deye): arm the Sell flag, send touDays, stop switching on the generator by @springfall2008 in #4591
• fix(teslemetry): assert optimization_strategy=economics on every tariff push by @springfall2008 in #4603

Docs and cleanup

• docs: add Canadian Solar EP Cube inverter setup by @SkiLtY in #4594
• fix: explain and stop wasting work when predbat.* history isn't recorded (#4583) by @springfall2008 in #4588

Full Changelog: v8.48.8...v8.49.0