feat(risk): Phase 1 safety - auto-flatten kill switch, portfolio VaR with Ledoit-Wolf, WAL crash recovery

Author: Ashutosh0x

Cargo.lock

@@ -18,4 +18,6 @@ compact_str = "0.8"
 tracing = "0.1"
 tokio = { version = "1.35", features = ["full"] }
 serde = { version = "1.0", features = ["derive"] }
+serde_json = "1.0"
+chrono = { version = "0.4", features = ["serde"] }
 statrs = "0.16"