chore: remove dead code, bump to 0.7.2

- Remove unused delete_master_key from crypto.rs
- Remove unused audit::log from audit.rs
- Simplify HistoryRow in rollback.rs (drop unused namespace/kind/name)
- Update AGENTS.md: audit::log → audit::log_tx

Made-with: Cursor

src/audit.rs

@@ -1,5 +1,5 @@
 use serde_json::Value;
-use sqlx::{PgPool, Postgres, Transaction};
+use sqlx::{Postgres, Transaction};
 
 /// Write an audit entry within an existing transaction.
 pub async fn log_tx(
@@ -30,35 +30,3 @@ pub async fn log_tx(
         tracing::debug!(action, namespace, kind, name, actor, "audit logged");
     }
 }
-
-/// Write an audit entry using the pool (fire-and-forget, non-fatal).
-/// Kept for future use or scenarios without an active transaction.
-#[allow(dead_code)]
-pub async fn log(
-    pool: &PgPool,
-    action: &str,
-    namespace: &str,
-    kind: &str,
-    name: &str,
-    detail: Value,
-) {
-    let actor = std::env::var("USER").unwrap_or_default();
-    let result: Result<_, sqlx::Error> = sqlx::query(
-        "INSERT INTO audit_log (action, namespace, kind, name, detail, actor) \
-         VALUES ($1, $2, $3, $4, $5, $6)",
-    )
-    .bind(action)
-    .bind(namespace)
-    .bind(kind)
-    .bind(name)
-    .bind(&detail)
-    .bind(&actor)
-    .execute(pool)
-    .await;
-
-    if let Err(e) = result {
-        tracing::warn!(error = %e, "failed to write audit log");
-    } else {
-        tracing::debug!(action, namespace, kind, name, actor, "audit logged");
-    }
-}