Move the capacity-risk signal (computeCapacityRisk), the settings-hydrate
guard, the re-enable-clears-dismissal behavior, the per-project dismiss
state, and the dismiss action into app/hooks/useCapacityRiskBanner.ts.
App computes agentStats / inProgressCount / inReviewCount / settings and
passes them in. Uses the named CapacityRiskSignal type (no ReturnType<typeof>).
Behavior-preserving; App.test.tsx identical (5 pre-existing failures, none
introduced). Verified by typecheck, eslint, and 3 renderHook tests (signal
computation, dismiss, re-enable-clears-dismissal after hydrate).
Part of U5 (App.tsx module-breakup plan).
b8c511fe38