maven: recall long-term memory in the query path (task 7)

Task 7 inserted note embeddings into the memory Store but nothing read them
back, and facts weren't indexed at all. Complete the read side:

- Facts are now embedded and inserted into memStore on capture (best-effort,
  never fails the fact write) — the notes table can't answer fact questions
  ("когда я пил воду?"), so memStore is their only recall path.
- Insert meta now carries text/ts/type so a Search hit is self-describing.
- IntentQuery consults memStore.Search after notes-RAG misses and before the
  general-knowledge phraser fallback (bestRecall, unit-tested). Strictly
  additive: it only runs once the notes path has already given up, so it can't
  regress existing recall. Note hits here overlap notes-RAG by design; the
  payoff is fact recall and a real read seam for a future persistent backend.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

cmd/mavend/recall.go

@@ -0,0 +1,25 @@
+package main
+
+import "github.com/kami/maven/internal/memory"
+
+// bestRecall is the read side of the long-term memory store: the top hit's
+// stored text when it clears the confidence gate. This recalls across BOTH
+// notes and facts (facts aren't in the notes table, so this is the only path
+// that can answer "when did I last …?" from a captured fact). A note hit here
+// is redundant with the notes-RAG path — by design; the two indexes can diverge
+// once the backend is swapped for a persistent/external store. ok=false when
+// there's no hit above the threshold or the hit carries no text.
+func bestRecall(results []memory.Result, min float64) (string, bool) {
+	if len(results) == 0 {
+		return "", false
+	}
+	top := results[0]
+	if top.Score < min {
+		return "", false
+	}
+	text := top.Meta["text"]
+	if text == "" {
+		return "", false
+	}
+	return text, true
+}

cmd/mavend/recall_test.go

@@ -0,0 +1,45 @@
+package main
+
+import (
+	"testing"
+
+	"github.com/kami/maven/internal/memory"
+)
+
+func TestBestRecall(t *testing.T) {
+	const min = 0.55
+
+	t.Run("empty results", func(t *testing.T) {
+		if _, ok := bestRecall(nil, min); ok {
+			t.Error("empty results returned ok")
+		}
+	})
+
+	t.Run("top below threshold", func(t *testing.T) {
+		res := []memory.Result{{Score: 0.4, Meta: map[string]string{"text": "выпил воды"}}}
+		if _, ok := bestRecall(res, min); ok {
+			t.Error("below-threshold hit returned ok")
+		}
+	})
+
+	t.Run("hit without text meta", func(t *testing.T) {
+		res := []memory.Result{{Score: 0.9, Meta: map[string]string{"type": "fact"}}}
+		if _, ok := bestRecall(res, min); ok {
+			t.Error("textless hit returned ok")
+		}
+	})
+
+	t.Run("clearing hit returns its text", func(t *testing.T) {
+		res := []memory.Result{
+			{Score: 0.82, Meta: map[string]string{"text": "выпил воды в три часа", "type": "fact"}},
+			{Score: 0.60, Meta: map[string]string{"text": "другое"}},
+		}
+		got, ok := bestRecall(res, min)
+		if !ok {
+			t.Fatal("clearing hit not returned")
+		}
+		if got != "выпил воды в три часа" {
+			t.Errorf("wrong text: %q", got)
+		}
+	})
+}