Active goal turns that stopped with text could hit the empty/unexpected-stop
continuation guards before threshold maintenance. When those guards scheduled
another goal turn, #checkCompaction never ran, so no auto_compaction_start was
emitted even while visible context stayed above thresholdTokens.
Run threshold maintenance once before those active-goal self-continuations and
log the threshold decision inputs: billed context, stored estimate, resolved
trigger tokens, post-maintenance tokens, strategy, threshold, promotion state,
and shouldCompact.
Also pass post-prune maintenance tokens into the shake recovery-band check so
supersede/drop-useless savings are preserved when deciding whether shake still
needs to fall back to context-full compaction.
Fixes#3174
roboomp
8ab754f636