brokerd: consult decisions record the body

Co-Authored-By: ornith-1.5-35b-a3b <agent@wntrmute.dev>

crates/bxcore/src/audit.rs

@@ -44,6 +44,9 @@ pub enum AuditEvent {
         grant_sha256: Option<Hash32>,
         taint: DataClass,
         untrusted: bool,
+        /// The JSON body `consult` would send (or sent). Other tools leave this unset.
+        #[serde(default, skip_serializing_if = "Option::is_none")]
+        body: Option<String>,
     },
     Approval {
         session: SessionId,

crates/bxcore/tests/records.rs

@@ -68,6 +68,7 @@ fn audit_records() {
                 grant_sha256: Some(seq_hash),
                 taint: DataClass::Private,
                 untrusted: false,
+                body: None,
             },
         ),
         record(
@@ -101,6 +102,7 @@ fn audit_records() {
                 grant_sha256: Some(rev_hash),
                 taint: DataClass::Secret,
                 untrusted: true,
+                body: None,
             },
         ),
         record(
@@ -155,6 +157,7 @@ fn audit_records() {
                 grant_sha256: None,
                 taint: DataClass::Private,
                 untrusted: false,
+                body: None,
             },
         ),
         record(