fix: use SteVecSelector for JsonAccessor (not SteVecTerm)

Both JsonPath and JsonAccessor specify which field to access in the
JSON structure, so both need SteVecSelector to generate the selector
index ("s" field) that eql_v2."->" expects.

Author: coderdan

packages/cipherstash-proxy/src/proxy/zerokms/zerokms.rs

@@ -172,13 +172,13 @@ impl EncryptionService for ZeroKms {
                         })
                         .unwrap_or(EqlOperation::Store),
 
-                    // JsonAccessor generates a term for SteVec field access (-> operator)
+                    // JsonAccessor generates a selector for SteVec field access (-> operator)
                     EqlTermVariant::JsonAccessor => col
                         .config
                         .indexes
                         .iter()
                         .find(|i| matches!(i.index_type, IndexType::SteVec { .. }))
-                        .map(|index| EqlOperation::Query(&index.index_type, QueryOp::SteVecTerm))
+                        .map(|index| EqlOperation::Query(&index.index_type, QueryOp::SteVecSelector))
                         .unwrap_or(EqlOperation::Store),
                 };