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

tsconfig.json

@@ -23,6 +23,7 @@
     { "path": "packages/util-agent" },
     { "path": "packages/agent-hermes" },
     { "path": "packages/agent-builtin" },
+    { "path": "packages/agent-mock" },
     { "path": "packages/agent-claude-code" },
     { "path": "packages/cli" }
   ]