Add VenueStep page (wizard step 7) + VenueCard selected prop

- Consolidated 3 baseline steps (venue select + venue detail + venue services) into 1
- CSS Grid venue card layout (1 col mobile, 2 col desktop) with radiogroup ARIA
- VenueCard extended with selected, role, aria-checked, tabIndex props
- Progressive disclosure: venue detail panel + service toggles after selection
- Service toggles via AddOnOption: photo presentation, livestream, recording
- Recording depends on streaming (auto-disabled when streaming off)
- Search input + filter chips for venue filtering
- Results count with aria-live, validation error with role="alert"
- Pre-planning variant with softer copy

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

src/components/pages/VenueStep/index.ts

@@ -0,0 +1,8 @@
+export { VenueStep, default } from './VenueStep';
+export type {
+  VenueStepProps,
+  VenueStepValues,
+  VenueStepErrors,
+  Venue,
+  VenueService,
+} from './VenueStep';