Agent runtime: LLM provider abstraction and metering proxy
Imported from GitHub issue El-SaMa/oma#83 by @El-SaMa.
Mirrors Hollahoop card: https://hollahoop.app/oma-portal/feedback/feature-requests/p/6b7b6269-5b81-4714-93a8-2fd1a67e04dd
Scope:
- Provider abstraction for OpenAI, Anthropic, OpenRouter.
- LLM calls routed through core-api for token counting and credit deduction.
- Server-side tool loop with schema validation.
- Confirmation flow for destructive or billable tools.
- Agent run/action ledger for audit and feedback.