Why: establish the authorized task workspace and its initial baseline.
Evidence: preserved precheck receipt in .task/feature-generative-ui-u5-scope.md; R0=259270b4e339132219490b95b42d12386f9abe1e.
Impact: task metadata only; the feature workspace starts at 259270b4e3.
Refs: .task/feature-generative-ui-u5-scope.md