P0: stand up executus harness module above majordomo

Batteries-included agent-harness base, extracted from mort's agent layer.
This first cut establishes the module + the zero-coupling core primitives:

- lane, dispatchguard, pendingattach, run/progress.go: moved verbatim from mort
- config: host config Source seam + env-var default (nil-safe helpers)
- deliver: output-egress seam + Discard/Stdout defaults
- identity: AdminPolicy + MemberResolver seams (nil-safe)
- fanout: programmatic N×M swarm (bounded global + per-key concurrency)
- README/CLAUDE.md with the vibe-coded banner; CI with Go gates +
  the "core stays majordomo+stdlib only" invariant

Core builds with stdlib only today; majordomo enters at P1 (model/structured).
go build/vet/test -race all green.

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

lane/precreate_test.go

@@ -0,0 +1,55 @@
+package lane
+
+import (
+	"context"
+	"sort"
+	"testing"
+)
+
+// TestRegistry_PreCreateMakesLanesVisible is the lane-level anchor for
+// hotfix-5 Bug 4. The mort.go boot path now pre-creates the well-known
+// lanes (skill-default, webhook-default, etc.) so they appear on
+// `/skills/admin/queues` and pass set-lane validation BEFORE any run
+// has ever hit them.
+//
+// Why this test (vs the existing GetOrCreate idempotency test): the
+// production bug was specifically about the registry's lazy-creation
+// behaviour combined with the queues page only listing materialised
+// lanes. This test asserts the missing piece: after pre-creation, both
+// Get and List return the lane immediately, regardless of whether a
+// job ever touched it.
+func TestRegistry_PreCreateMakesLanesVisible(t *testing.T) {
+	r := NewRegistry(nil)
+	wellKnown := []string{
+		"ollama", "anthropic-thinking", "anthropic-default", "llm-default",
+		"skill-default", "skill-heavy", "webhook-default",
+	}
+	ctx := context.Background()
+	for _, name := range wellKnown {
+		_ = r.GetOrCreate(ctx, name)
+	}
+	// Get must return non-nil for every lane WITHOUT going through
+	// GetOrCreate again — that's the pre-creation guarantee.
+	for _, name := range wellKnown {
+		if l := r.Get(name); l == nil {
+			t.Errorf("lane %q not registered after pre-create; admin "+
+				"queues page would be missing it (Bug 4 regression)", name)
+		}
+	}
+	// List must enumerate every pre-created lane.
+	got := make([]string, 0)
+	for _, l := range r.List() {
+		got = append(got, l.Name())
+	}
+	sort.Strings(got)
+	want := append([]string{}, wellKnown...)
+	sort.Strings(want)
+	if len(got) != len(want) {
+		t.Fatalf("List length: got %d, want %d (got=%v, want=%v)", len(got), len(want), got, want)
+	}
+	for i := range want {
+		if got[i] != want[i] {
+			t.Errorf("List[%d]: got %q, want %q", i, got[i], want[i])
+		}
+	}
+}