SAFETY-128: control does not act on late Home Assistant readings

Readings that Home Assistant delivers late but still changing passed
every staleness gate, so the loop corrected again each cycle an error
its last command had already fixed (10 s late: the give run swung and
exported to -1.9 kW), and the peak guard pushed to the inverter limit
on the same late figures (OPT-34 F-2).

app/lateness.py fits how long after a power request the meter shows
it. Over 8 s the readings are late: a request the battery reading has
not answered holds the loop (it may not lead the reading by more than
100 W) and caps the peak guard at what stands; unanswered for 23 s it
holds, then 0 W after stale_input_s. An amber row and one log line per
episode say so. With readings on time nothing changes (digests equal).

DECISIONS/SAFETY-128-late-readings.md; test_safety128.py.

Co-Authored-By: Claude <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Bdqr7PiaHcBnzPituu2yTC

goodwe_controller/CHANGELOG.md

@@ -2,6 +2,10 @@
 
 ## 0.20.0
 
+### Not in a release yet
+
+- When Home Assistant passes readings on late, control no longer swings on them: it waits until the battery shows its last power request, and the peak limit no longer asks for full power on them. The page says so, and if the readings stay too late every inverter goes to 0 W ([[SAFETY-128]]).
+
 **A minor bump: a Forecast tab, a night grid charge sized to what the sun will not give, a kept evening forecast, and no option changes.**
 No option was added, removed or renamed, and no default changed (86 options). It is a minor bump because Leftover solar now buys different amounts from the grid and the night charge keeps its level when the forecast goes quiet; every saved setting still starts.
 **Existing installs need no option change:** options that start 0.19.2 also