store, mavend: a fact is indexed as the fact, not as the utterance (V-493)

queryMemory returns a fact's stored text verbatim, so the text the write path
indexed is what he hears. It was the utterance, which made recall of any
voice-tapped fact answer with the sentence he said: go_version = 1.20 was
indexed as "какая последняя версия языка Go?", and that question came back.

FactRecallText renders the fact instead, and the utterance stays in meta as
provenance. Correcting a value now drops the key's vectors the way voiding one
does, since the superseded value was still answering.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

cmd/mavend/factgate_test.go

@@ -78,6 +78,22 @@ func TestActionFact_ExplicitCaptureStillWrites(t *testing.T) {
 	if f.Confidence != 1.0 {
 		t.Errorf("confidence = %v, want 1.0 for a value he said", f.Confidence)
 	}
+	// #493: what recall reads back is the fact, not the sentence he said.
+	// queryMemory returns a fact's text verbatim, so the utterance sitting here
+	// meant "запиши что я пил воду" was the answer to "когда я пил воду?".
+	hits, err := h.memStore.Search(ctx, mustEmbedPassage(t, h, "вода"), 3)
+	if err != nil {
+		t.Fatalf("memory search: %v", err)
+	}
+	if len(hits) != 1 {
+		t.Fatalf("the fact was not indexed once: %+v", hits)
+	}
+	if got := hits[0].Meta["text"]; got != "water — вода" {
+		t.Errorf("indexed text = %q, want the fact", got)
+	}
+	if got := hits[0].Meta["utterance"]; got != "запиши что я пил воду" {
+		t.Errorf("utterance provenance = %q, want it kept alongside", got)
+	}
 }
 
 func TestFactConfidence(t *testing.T) {