fix(render): last() silently returns nil for []*entity.Entity slices (#101)

last() handled []string and []interface{} but was missing the
[]*entity.Entity case that first() already had. Any template calling
{{ last .Entities }} on an entity list would receive nil and produce
a silent empty output instead of the last entity.

Also adds TestFirstLast_EntitySlice covering both functions with entity
slices, including empty-slice behaviour.

Co-authored-by: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: greynewell

internal/archdocs/pssg/render/funcs.go

@@ -227,6 +227,10 @@ func last(list interface{}) interface{} {
 		if len(v) > 0 {
 			return v[len(v)-1]
 		}
+	case []*entity.Entity:
+		if len(v) > 0 {
+			return v[len(v)-1]
+		}
 	}
 	return nil
 }

internal/archdocs/pssg/render/funcs_test.go

@@ -2,6 +2,8 @@ package render
 
 import (
 	"testing"
+
+	"github.com/supermodeltools/cli/internal/archdocs/pssg/entity"
 )
 
 func TestFormatNumber(t *testing.T) {
@@ -76,6 +78,28 @@ func TestSliceHelper(t *testing.T) {
 	}
 }
 
+func TestFirstLast_EntitySlice(t *testing.T) {
+	a := &entity.Entity{Slug: "a"}
+	b := &entity.Entity{Slug: "b"}
+	c := &entity.Entity{Slug: "c"}
+	entities := []*entity.Entity{a, b, c}
+
+	if got := first(entities); got != a {
+		t.Errorf("first([]*entity.Entity) = %v, want %v", got, a)
+	}
+	if got := last(entities); got != c {
+		t.Errorf("last([]*entity.Entity) = %v, want %v", got, c)
+	}
+
+	var empty []*entity.Entity
+	if got := first(empty); got != nil {
+		t.Errorf("first(empty []*entity.Entity) = %v, want nil", got)
+	}
+	if got := last(empty); got != nil {
+		t.Errorf("last(empty []*entity.Entity) = %v, want nil", got)
+	}
+}
+
 func TestSortStrings(t *testing.T) {
 	input := []string{"c", "a", "b"}
 	got := sortStrings(input)