feat(trace+ai): add cubetrace package and wire DBT/AI/CUBEsys command + module edits (green-lit WIP)

Brings in the cubetrace crate (PDF Package 4, §547): wraps a DBI engine via an
FFI seam and streams trace events (basic blocks, syscalls) into cubestore,
tagging each with CZYX coordinates and header flags.

- Cargo.toml: register cubetrace workspace member
- cubeai/src/lib.rs, cubedbt/src/lib.rs: DBT/AI rule + trace integration edits
- cubecode/src/{cb,cell}.rs: code-cell bytecode/module plumbing for traces
- cubesys/src/commands.rs: trace/AI command surface expansion
- cubetrace/: new crate (builds; 2 non-fatal warnings)

All layers of the OS-in-CUBE migration pass; recorded per user green-light.

Cargo.toml

@@ -9,6 +9,7 @@ members = [
     "cubesys",
     "cubedbt",
     "cubeai",
+    "cubetrace",
     "cube-bench",
 ]