Migrate run creation and validation through CoreGateway

[quinCode]

Migrate run creation and validation through CoreGateway

Parent

#2

What to build

Migrate run draft validation and run creation into the new architecture. The React configuration flow should submit a typed run draft to the UI backend, the backend should validate through application services and CoreGateway, and successful requests should start a core run through the CLI contract.

This slice includes existing model dependency check behavior where it is part of the current run validation workflow, but does not add new model management UI scope.

Acceptance criteria

• UI backend exposes typed run validation and run creation routes.
• CoreGateway validates run requests and starts runs through intention-level methods.
• Temporary run configuration generation stays behind backend services and does not leak into React.
• React feature submits run drafts through generated API client types.
• Validation errors and model dependency failures are normalized into UI application model responses.
• Backend tests cover successful validation, missing config references, missing inputs, credential failures, and start-run command construction.
• Frontend tests cover validation success, validation errors, and run submission state.

Blocked by

• Migrate catalog and schema-driven configuration as the first full feature module #7