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- Removed outdated unit tests that relied on DuckDB and replaced them with tests using PgStore.

docs/architecture/README.md

@@ -8,7 +8,7 @@ Primary goals:
 
 - Detect and execute triangular opportunities on Kraken with fee/slippage-aware math.
 - Keep hot-path latency low with incremental order-book updates and event-driven scoring.
-- Persist operational data in DuckDB for dev, test, and prod.
+- Persist operational data in PostgreSQL for all environments.
 - Provide operator controls, audit trail, and alerting through a server-rendered dashboard.
 - Support backtesting, parameter sweeps, and deferred experimental strategy work behind feature flags.
 
@@ -17,7 +17,7 @@ Primary goals:
 - Python 3.12+ runtime.
 - Native Kraken WebSocket on the hot path.
 - HTMX + Jinja2 UI, no SPA build step.
-- DuckDB everywhere.
+- PostgreSQL everywhere.
 - Self-hosted Gitea Actions CI and Gitea registry.
 - Windows development support.
 - Secrets must stay out of the repository.
@@ -32,7 +32,7 @@ The bot consumes Kraken market data, detects opportunities, and executes trades
 
 - Kraken REST + WebSocket provide market data and execution.
 - FastAPI serves HTML fragments, JSON endpoints, and SSE streams.
-- DuckDB stores trades, opportunities, snapshots, audit events, and runtime state.
+- PostgreSQL stores trades, opportunities, snapshots, audit events, and runtime state.
 - Coolify can deploy the published image using environment variables and persistent storage.
 
 ## 4. Solution Strategy
@@ -55,7 +55,7 @@ The bot consumes Kraken market data, detects opportunities, and executes trades
 - `execution/` - multi-leg trade sequencing.
 - `backtesting/` - replay engine, parameter sweep, experiment scaffolds.
 - `strategy/` - experimental strategy modules such as stat-arb.
-- `storage/` - DuckDB schema and repositories.
+- `storage/` - PostgreSQL schema and repositories.
 - `alerting/` - multi-channel notifications.
 - `runtime/` - startup recovery and graceful shutdown.
 
@@ -64,7 +64,7 @@ The bot consumes Kraken market data, detects opportunities, and executes trades
 - `fastapi`, `uvicorn`, `jinja2`, `htmx`-driven templates.
 - `orjson` for low-alloc parsing.
 - `sortedcontainers` for book state.
-- `duckdb` for persistence and analytics.
+- `asyncpg` for PostgreSQL persistence.
 - `pydantic` / `pydantic-settings` for typed configuration.
 - `cryptography` / keyring for secret handling.
 
@@ -77,7 +77,7 @@ The bot consumes Kraken market data, detects opportunities, and executes trades
 3. Incremental detector scores impacted cycles.
 4. Risk manager validates the opportunity.
 5. Execution sequencer places legs if approved.
-6. Trades and snapshots persist to DuckDB.
+7. Trades and snapshots persist to PostgreSQL.
 7. Dashboard and alerts reflect state changes.
 
 ### 6.2 Dashboard Control Flow
@@ -112,7 +112,7 @@ The bot consumes Kraken market data, detects opportunities, and executes trades
 
 - Deploy from the published image.
 - Configure runtime via environment variables.
-- Mount persistent storage at `/app/data` for DuckDB.
+- Connect to PostgreSQL at configured `PG_HOST`.
 
 ## 8. Cross-Cutting Concepts
 
@@ -126,7 +126,7 @@ The bot consumes Kraken market data, detects opportunities, and executes trades
 ## 9. Architecture Decisions
 
 - Native Kraken WS instead of a generic exchange abstraction on the hot path.
-- DuckDB as the single database engine.
+- PostgreSQL as the single database engine.
 - HTMX + Jinja2 instead of SPA frontend.
 - Backtesting reuses production detector/risk/execution logic.
 - Experimental stat-arb stays behind a feature flag.
@@ -152,5 +152,5 @@ The bot consumes Kraken market data, detects opportunities, and executes trades
 - WS: WebSocket.
 - HTMX: HTML-over-the-wire UI library.
 - SSE: Server-Sent Events.
-- DUCKDB: Embedded analytical database used for all environments.
+- PGSQL: PostgreSQL database used for all environments.
 - Stat arb: Statistical arbitrage, currently experimental and feature-flagged.