mavend: group the recall fields into one wiring struct (V-433)

The review comment asked for basic DI. The answer is the idiom voice.go
already had for capabilities — a cohesive *Wiring struct — applied to a
group that is not a capability toggle, plus the decision written down so
it is a rule and not a habit.

recallWiring holds the embedder, the vector store, the personal boundary
and the two numbers that gate an answer. They sat in three places on
reactiveHandler, with the gate numbers a hundred lines from the store
they gate. Its zero value means no recall, so it is a value, not a
pointer like the optional-capability groups.

dataStore stays out of it. patterns.go, ecosystem_acts.go and confirm.go
use it, so it is not part of this cluster.

docs/handler-wiring.md records the choice, rejects a container or a
wire-style generator outright, defers narrow per-handler interfaces to
the package split that would justify them, and states the constraint the
task named: a wiring change does not ride a feature PR.

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

cmd/mavend/query_recall_test.go

@@ -85,15 +85,17 @@ func buildRecallHandler(t *testing.T, question string, mems []recallCase) (*reac
 
 	phr := &recordingPhraser{Stub: phraser.NewStub()}
 	h := &reactiveHandler{
-		api:             ipc.NewStoreAPI(st),
-		embedder:        emb,
+		api: ipc.NewStoreAPI(st),
+		recall: recallWiring{
+			embedder:  emb,
+			memStore:  mem,
+			minScore:  0.55,
+			minMargin: 0.008,
+		},
 		replier:         voice.NewStubReplier(),
 		phraser:         phr,
 		now:             func() time.Time { return now },
-		memStore:        mem,
 		dataStore:       st,
-		queryMinScore:   0.55,
-		queryMinMargin:  0.008,
 		weatherProvider: nil,
 	}
 	return h, phr