feat(dbt+ai): build out cubedbt and cubeai packages (Package 4, PDF §549/§551)

cubedbt: DBT runtime that reads CZYX-stored translation rules and patches
them into a code cache to execute mimicked behavior. TranslationRule (CZYX
Variant record in c220 band) maps an op-class to a replacement bytecode
fragment; CodeCache patches an original CodeCell under eligible rules and
writes the result as a Variant (preserving behavior descriptors), and
DbRuntime.mimic() fetches -> patches -> runs in the real Vm, proving
're-run or modify behavior without the original binary'.

cubeai: models over cube-stored traces/graphs to classify blocks
(Computation/Branch/CallTrampoline/IoSection/Sequence from the op-class
histogram + behavior descriptors) and suggest new code sequences as
cubedbt TranslationRules (persisted into the c220 rule band, discoverable
by DbRuntime). End-to-end: trace -> classify -> suggest -> mimic.

Both crates are dependency-free and operate on the real CubeStore/CodeCell/
Vm/Behavior types, so they are exercisable today on HashBackend and slot
into ConcurrentStore later without an API change. ./check quick green:
cubedbt 4 tests, cubeai 5 tests, full workspace green.

Cargo.toml

@@ -7,6 +7,8 @@ members = [
     "cubecode",
     "cubecrypt",
     "cubesys",
+    "cubedbt",
+    "cubeai",
     "cube-bench",
 ]