feat: add uwf skill cli command and Prepare section in role prompt

- Add 'uwf skill cli' command that prints markdown CLI reference
- buildRolePrompt now generates ## Prepare section:
  - Always prompts agent to run 'uwf skill cli' (explicit skill)
  - Renders capabilities as keyword hints for implicit skill loading

Fixes #369

packages/cli-workflow/src/cli.ts

@@ -14,6 +14,7 @@ import {
   cmdCasWalk,
 } from "./commands/cas.js";
 import { cmdSetup, cmdSetupInteractive } from "./commands/setup.js";
+import { cmdSkillCli } from "./commands/skill.js";
 import {
   cmdThreadFork,
   cmdThreadKill,
@@ -220,6 +221,15 @@ thread
     });
   });
 
+const skill = program.command("skill").description("Built-in skill references for agents");
+
+skill
+  .command("cli")
+  .description("Print a markdown reference of all uwf commands")
+  .action(() => {
+    console.log(cmdSkillCli());
+  });
+
 program
   .command("setup")
   .description("Configure provider, model, and agent")