Add ProvidersStep page (wizard step 2) + audit fixes

ProvidersStep: list-map split layout with provider card list (left)
and map slot (right). SearchBar + filter chips + radiogroup card
selection pattern. Back link, results count with aria-live,
grief-sensitive copy with pre-planning variant. Pure presentation.

Audit fixes (18/20):
- P1: Move role="radio" + aria-checked onto ProviderCard (focusable)
- P3: Add aria-live="polite" on results count
- ProviderCard: extend props to accept HTML/ARIA passthrough, add
  rest spread to Card for role/aria-checked/aria-label support

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

src/components/molecules/ProviderCard/ProviderCard.tsx

@@ -13,8 +13,8 @@ import { Typography } from '../../atoms/Typography';
 
 // ─── Types ───────────────────────────────────────────────────────────────────
 
-/** Props for the FA ProviderCard molecule */
-export interface ProviderCardProps {
+/** Own props for the FA ProviderCard molecule (excludes HTML/Card passthrough) */
+export interface ProviderCardOwnProps {
   /** Provider display name */
   name: string;
   /** Location text (suburb, city) */
@@ -45,6 +45,10 @@ export interface ProviderCardProps {
   sx?: SxProps<Theme>;
 }
 
+/** Props for the FA ProviderCard molecule — includes HTML/ARIA passthrough to Card */
+export type ProviderCardProps = ProviderCardOwnProps &
+  Omit<React.HTMLAttributes<HTMLDivElement>, keyof ProviderCardOwnProps>;
+
 // ─── Constants ───────────────────────────────────────────────────────────────
 
 const LOGO_SIZE = 'var(--fa-provider-card-logo-size)';
@@ -102,6 +106,7 @@ export const ProviderCard = React.forwardRef<HTMLDivElement, ProviderCardProps>(
       startingPrice,
       onClick,
       sx,
+      ...rest
     },
     ref,
   ) => {
@@ -115,6 +120,7 @@ export const ProviderCard = React.forwardRef<HTMLDivElement, ProviderCardProps>(
         selected={selected}
         padding="none"
         onClick={onClick}
+        {...rest}
         sx={[
           {
             overflow: 'hidden',