feat(14.3-01): add summer new with a starter route and relative go.work

- build.NewApp writes sm-<name>-app: go.mod with a relative framework
  replace, go.work, summer.yaml, config/ and a starter plugin
- make:plugin gains an opt-in starter route (GET /{$}) in the same
  routes.go template; plain make:plugin output is unchanged
- plugin:add writes go.work use paths relative to the go.work directory
- bonfire accepts new as a bare tool command name

modules/bonfire/command.go

@@ -109,7 +109,7 @@ func (in cobraInput) Flag(name string) (string, bool) {
 
 func validCommandName(name string) bool {
 	switch name {
-	case "build", "dev", "serve", "migrate":
+	case "build", "dev", "new", "serve", "migrate":
 		return true
 	}
 	ns, verb, ok := strings.Cut(name, ":")