feat(14.3-01): detect the framework checkout and guard summer new targets

- resolve the framework from --framework, then a sibling summercms or
  summercms.go checkout, then the binary's own source tree, each accepted
  only when its go.mod declares the framework module
- refuse a missing parent and a target inside the framework checkout
- remove the half-written app when any step fails
- add --no-plugin for an app with no starter plugin

cmd/summer/main.go

@@ -309,7 +309,8 @@ func newCommand() bonfire.Command {
 			Required:    true,
 		}},
 		Flags: []bonfire.Flag{
-			{Name: "framework", Description: "Path to the framework checkout"},
+			{Name: "framework", Description: "Path to the framework checkout (default: a sibling summercms or summercms.go checkout)"},
+			{Name: "no-plugin", Description: "Do not create the starter plugin", Bare: true},
 		},
 		Run: func(ctx context.Context, in bonfire.Input, out bonfire.Output) error {
 			name, ok := in.Argument("name")
@@ -325,6 +326,7 @@ func newCommand() bonfire.Command {
 				Name:      name,
 				Parent:    dir,
 				Framework: framework,
+				NoPlugin:  flagTrue(in, "no-plugin"),
 			}, out)
 			return err
 		},