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- Removed outdated unit tests that relied on DuckDB and replaced them with tests using PgStore.

pyproject.toml

@@ -54,7 +54,7 @@ pretty = true
 mypy_path = "src"
 
 [[tool.mypy.overrides]]
-module = ["duckdb", "keyring", "sortedcontainers"]
+module = ["asyncpg", "keyring", "sortedcontainers"]
 ignore_missing_imports = true
 
 [tool.pytest.ini_options]