Add integration tests for execution persistence, metrics, and opportunity writing

- Implemented integration tests for the execution writer to ensure trade orders and PnL are persisted correctly.
- Created integration tests for the metrics calculator to summarize execution data accurately.
- Added integration tests for the opportunity writer to verify event persistence.
- Established PostgreSQL schema validation tests to ensure all expected tables, columns, and constraints exist.
- Removed outdated unit tests that relied on DuckDB and replaced them with tests using PgStore.

requirements/latest-dev.in

@@ -1,4 +1,5 @@
 # Unpinned dev dependencies (latest available)
+asyncpg-stubs
 black
 mypy
 pre-commit

requirements/latest-runtime.in

@@ -1,6 +1,6 @@
 # Unpinned runtime dependencies (latest available)
+asyncpg
 cryptography
-duckdb
 fastapi
 httptools
 httpx