fix(agent-runtime): repair flat decision contract

[christopherjnelson]

Summary

• restore self-contained goal and memory sentinel rules in the OpenRouter v8 prompt
• return actionable goal and memory validation codes for automatic repair
• add realistic flat-response coverage and schema-current initial/stateful smoke fixtures
• fix pnpm-forwarded smoke CLI argument parsing

Validation

• repository owner confirmed format, lint, typecheck, tests, build, and Playwright all pass
• pnpm smoke:openrouter -- google/gemini-3.7-flash initial
• pnpm smoke:openrouter -- google/gemini-3.7-flash stateful

Both real-provider smoke scenarios returned valid normalized decisions.