invalidate() only dropped the rule cache, not the per-(unit,rule) state machine —
so editing a rule's metric/threshold left a stale 'active' phase that mis-evaluated
against the new config (spurious clear, or suppressed onset), and deleting an
in-alarm rule left an open AlertEvent that kept the client portal stuck "in alarm"
forever. update/delete now call _reset_rule_runtime: forget_rule() drops the state
machine and any open event for that rule is closed.
Verified: existing evaluator tests + cooldown scenario still pass; compiles.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>