refactor: rename workflow-agent-kit → workflow-util-agent, merge workflow-moderator into cli-workflow

- Rename packages/workflow-agent-kit → packages/workflow-util-agent
- Update all imports, tsconfig references, docs
- Delete dead file packages/workflow-util-agent/src/build-agent-prompt.ts
- Merge workflow-moderator (62 LOC) into cli-workflow/src/moderator/
- Move workflow-moderator to legacy-packages/
- Add mustache dependency to cli-workflow
- Update publish-all.mjs

Fixes #512

packages/workflow-util-agent/tsconfig.json

@@ -0,0 +1,9 @@
+{
+  "extends": "../../tsconfig.json",
+  "compilerOptions": {
+    "rootDir": "src",
+    "outDir": "dist"
+  },
+  "include": ["src"],
+  "references": [{ "path": "../workflow-protocol" }]
+}