feat: add agent-mock package for deterministic E2E testing (#33)

New package @united-workforce/agent-mock (uwf-mock CLI):
- Reads pre-scripted outputs from a YAML mock data file (--mock-data)
- Counts existing CAS chain steps to determine step index
- Validates expected role matches actual moderator routing
- Stores minimal detail node in CAS for valid step refs
- Zero LLM, instant execution, 100% deterministic

Usage in config.yaml:
  agents:
    mock:
      command: uwf-mock
      args: ["--mock-data", "./fixtures/scenario.yaml"]

Refs #33

packages/agent-mock/package.json

@@ -0,0 +1,47 @@
+{
+  "name": "@united-workforce/agent-mock",
+  "version": "0.5.0",
+  "files": [
+    "src",
+    "dist",
+    "package.json"
+  ],
+  "type": "module",
+  "bin": {
+    "uwf-mock": "./src/cli.ts"
+  },
+  "exports": {
+    ".": {
+      "types": "./dist/index.d.ts",
+      "import": "./dist/index.js"
+    }
+  },
+  "scripts": {
+    "prepublishOnly": "echo 'Use pnpm run release from repo root' && exit 1",
+    "test": "vitest run __tests__/",
+    "test:ci": "vitest run __tests__/"
+  },
+  "dependencies": {
+    "@ocas/core": "^0.3.0",
+    "@united-workforce/protocol": "workspace:^",
+    "@united-workforce/util": "workspace:^",
+    "@united-workforce/util-agent": "workspace:^",
+    "yaml": "^2.9.0"
+  },
+  "devDependencies": {
+    "typescript": "^5.8.3"
+  },
+  "publishConfig": {
+    "access": "public"
+  },
+  "repository": {
+    "type": "git",
+    "url": "https://git.shazhou.work/shazhou/united-workforce.git",
+    "directory": "packages/agent-mock"
+  },
+  "homepage": "https://git.shazhou.work/shazhou/united-workforce#readme",
+  "bugs": {
+    "url": "https://git.shazhou.work/shazhou/united-workforce/issues"
+  },
+  "license": "MIT"
+}