feat: add actor skill — frontmatter protocol + CAS reference

Adds 'uwf skill actor' command for agents executing workflow roles.
Covers the two things an actor needs to know:
1. Frontmatter output protocol (status field, schema-defined fields)
2. CAS operations (put, get, refs, walk, merkle DAG pattern)

Refs #540

packages/cli-workflow/src/cli.ts

@@ -17,6 +17,7 @@ import { cmdConfigGet, cmdConfigList, cmdConfigSet } from "./commands/config.js"
 import { cmdLogClean, cmdLogList, cmdLogShow } from "./commands/log.js";
 import { cmdSetup, cmdSetupInteractive } from "./commands/setup.js";
 import {
+  cmdSkillActor,
   cmdSkillArchitecture,
   cmdSkillCli,
   cmdSkillList,
@@ -503,6 +504,13 @@ skill
     console.log(cmdSkillYaml());
   });
 
+skill
+  .command("actor")
+  .description("Print the actor reference (frontmatter protocol + CAS)")
+  .action(() => {
+    console.log(cmdSkillActor());
+  });
+
 skill
   .command("moderator")
   .description("Print the moderator reference")