docs: note panel sidetone default fix in plan

docs/superpowers/plans/2026-08-31-headsetcontrol-plugin.md

@@ -764,7 +764,7 @@ local state = {
 
 local INACTIVE_VALUES = { 0, 1, 2, 5, 10, 15, 20, 30, 45, 60, 90 }
 local INACTIVE_LABELS = { noctalia.tr("panel.never"), "1", "2", "5", "10", "15", "20", "30", "45", "60", "90" }
-local committedSidetone = 64
+local committedSidetone = noctalia.getConfig("sidetone_default") or 64
 
 local function syncState()
   local v = noctalia.state.get("device")