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/fact_subject_test.go

@@ -28,11 +28,10 @@ func TestApplyAction_FactCapture_QueuesEntityResolution(t *testing.T) {
 
 	h := &reactiveHandler{
 		api:       api,
-		embedder:  emb,
+		recall:    recallWiring{embedder: emb, memStore: memory.NewInMemoryStore()},
 		router:    rtr,
 		replier:   voice.NewStubReplier(),
 		now:       func() time.Time { return now },
-		memStore:  memory.NewInMemoryStore(),
 		dataStore: st,
 	}