Flip the 4 TS a2ui builders (shared/typescript + mastra,
claude-sdk-typescript, langgraph-typescript) from the legacy flat
operation shape to v0.9 nested (createSurface / updateComponents /
updateDataModel), matching the Python builder and what A2UI consumers
process. Flat ops were never processed as valid nested operations, so
the surface schema and components were never applied.
Also align the empty-data guard to Python's `if data:` semantics (empty
object -> no updateDataModel), add a v0.9 parity guard test to all 4
test files, and add 12 gen-ui-a2ui-fixed aimock fixtures.
Jordan Ritter