P4: persona noun — Agent + ToRunnable bridge + Memory store

The headline P4 piece (clean redesign): the Agent persona noun, decoupled from
its Discord shell.
- agent.go/storage.go/builtin_loader.go moved from mort's pkg/logic/agents; the
  Storage seam drops the Discord CommandBindingStorage embedding (a host
  concern). The host-entangled files (commands, chatbot_provider, command-
  binding dispatcher, personalization, system) stay in mort.
- runnable.go: Agent.ToRunnable() lowers a persona into run.RunnableAgent — the
  bridge that lets run.Executor run a persona without importing this battery
  (the inversion of agentexec.Run(*agents.Agent)).
- memory.go: NewMemory() — zero-dep in-process persona Storage (all 11 CRUD +
  trigger-query methods).

Tests: ToRunnable field/phase mapping; Memory round-trip. CI invariant: core
imports ZERO from persona.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

persona/persona_test.go

@@ -0,0 +1,45 @@
+package persona
+
+import (
+	"context"
+	"testing"
+	"time"
+)
+
+func TestToRunnable(t *testing.T) {
+	a := &Agent{
+		ID: "id1", Name: "helper", SystemPrompt: "be nice", ModelTier: "fast",
+		MaxIterations: 5, MaxRuntime: 30 * time.Second,
+		LowLevelTools: []string{"think"}, SkillPalette: []string{"animate"},
+		CriticEnabled: true, CriticBackstopMultiplier: 2,
+		Phases: []AgentPhase{{Name: "p1", ModelTier: "thinking", MaxIter: 3, Tools: []string{"now"}, Optional: true}},
+	}
+	r := a.ToRunnable()
+	if r.ID != "id1" || r.ModelTier != "fast" || r.MaxIterations != 5 || !r.Critic.Enabled {
+		t.Fatalf("ToRunnable mapping wrong: %+v", r)
+	}
+	if len(r.Phases) != 1 || r.Phases[0].MaxIterations != 3 || !r.Phases[0].Optional {
+		t.Fatalf("phase mapping wrong: %+v", r.Phases)
+	}
+}
+
+func TestMemoryStoreRoundTrip(t *testing.T) {
+	ctx := context.Background()
+	m := NewMemory()
+	a := &Agent{ID: "a1", Name: "n", OwnerID: "o1"}
+	if err := m.SaveAgent(ctx, a); err != nil {
+		t.Fatal(err)
+	}
+	got, err := m.GetAgent(ctx, "a1")
+	if err != nil || got.Name != "n" {
+		t.Fatalf("GetAgent: %v %+v", err, got)
+	}
+	byName, err := m.GetAgentByName(ctx, "o1", "n")
+	if err != nil || byName.ID != "a1" {
+		t.Fatalf("GetAgentByName: %v %+v", err, byName)
+	}
+	list, _ := m.ListAgents(ctx, "o1")
+	if len(list) != 1 {
+		t.Fatalf("ListAgents = %d", len(list))
+	}
+}