fix(protocol): keep generic trace schema compatible with v2 and v3

Split standalone v2/v3 schemas and drop TraceV2 deny_unknown_fields so legacy traces with extra keys still parse; mix and version checks stay in RecordedTrace.

crates/bsk-protocol/src/tools/mod.rs

@@ -11,6 +11,7 @@ pub mod observation;
 pub mod record;
 mod record_common;
 mod record_v2;
+mod record_v3;
 pub mod script;
 pub mod session;
 pub mod tabs;