feat: Implement latency profiling and guardrails for performance monitoring

- Added synthetic latency profiler scenarios and CLI scripts for baseline generation and regression checks.
- Introduced latency baseline and threshold artifacts for CI enforcement.
- Enhanced CI workflow with latency guardrail checks.
- Updated documentation to include latency profiling commands and performance metrics.
- Added unit tests for latency guardrail evaluation.

CHANGELOG.md

@@ -15,6 +15,8 @@
 - Added `runtime_state_snapshots` persistence for control flags, open trade count, and last known balances.
 - Added CI security gates for dependency auditing (`pip-audit --strict`) and a repository/worktree secret scan script.
 - Added strict settings validators for auth pairing, Kraken credential pairing, alert severity bounds, and key-scope policy.
+- Added synthetic latency profiler scenarios and CLI scripts for baseline generation and regression checks.
+- Added latency baseline/threshold artifacts and CI latency guardrail enforcement.
 
 ### Changed
 
@@ -22,6 +24,7 @@
 - Added configuration env keys for stop-condition thresholds.
 - WebSocket client now emits system alerts for disconnect/reconnect and heartbeat staleness timeout events.
 - Added explicit Kraken API key permission configuration (`KRAKEN_API_KEY_PERMISSIONS`) and docs for least-privilege key usage.
+- Optimized dashboard metrics aggregation to use DuckDB SQL aggregates/quantiles instead of Python row scans.
 
 ### Removed
 
@@ -50,3 +53,4 @@
 - Added startup restart safety guard that halts execution when open trades are detected after restart.
 - Added lifecycle tests for snapshot persistence, worker draining, recovery restore, and startup reconciliation hook.
 - Added unit coverage for security-related settings validation paths.
+- Added latency guardrail unit coverage and documented measured metrics aggregation speedup (`1.14x`).