[Minor] Migrate rules/controller/neural.lua to lua_shape

[Minor] Migrate rules/controller/neural.lua to lua_shape

Replace tableshape with lua_shape in neural controller.

Changes:
- ts.shape { ... } → T.table({ ... })
- ts.array_of(ts.array_of(x)) → T.array(T.array(x))
- ts.string, ts.number → T.string(), T.number()
- :is_optional() → :optional()
- Added comprehensive documentation to all fields

Schema: learn_request_schema for neural network training requests
with nested arrays for ham and spam training vectors.