Add ConfigStore class providing async access to config schema:
- get_adapter/list_adapters/upsert_adapter for adapter config
- pause_adapter/unpause_adapter for runtime control
- set_api_key/get_api_key with encryption via crypto.py
- listen_for_changes using Postgres LISTEN/NOTIFY
Includes Pydantic models (AdapterConfig, ApiKeyInfo) and tests
using real Postgres test database.
Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>
