mesh-knowledge: clear a never-reviewed notice once the record moves on, key it by version and run of tries, say times locally (review of #219)

A notice left open kept telling the operator a record was proposed and not in force after it was proposed again
or accepted, and a later version's notice merged into it.

modules/mesh-knowledge/cmd/mesh-knowledge/kb.go

@@ -67,6 +67,9 @@ type Judgement func(question string, schema map[string]any, model string) (json.
 // Notifier tells the operator's channel something (operator-channel.notify).
 type Notifier func(key, summary, headline, explanation string) error
 
+// Clearer tells the operator's channel that what it was told under key is over, in one resolved line.
+type Clearer func(key, resolved string) error
+
 // KB is the knowledge base.
 type KB struct {
 	Store    Store
@@ -75,6 +78,7 @@ type KB struct {
 	Judge    Judgement
 	Asks     AskBus
 	Notify   Notifier
+	Clear    Clearer
 	Emit     func(event string, body any) error
 	Settings func() (Settings, error)
 	Now      func() time.Time