fix(mobile): announce which Show and rating chip is chosen

MChip only showed its state through colour. A pressable option renders
aria-pressed from active; the places filter's Show and rating floor chips use
it, and the tests now check the chosen chip by its pressed state.

client/src/mobile/components/MChip.tsx

@@ -10,16 +10,23 @@ interface MChipProps {
    * back what it can: the chips that start a search are the ones worth the height.
    */
   size?: 'sm' | 'tap'
+  /**
+   * The chip is one choice of a picker: announce `active` as `aria-pressed`, so a
+   * screen reader hears which one is on, not just its colour. Off by default, for
+   * chips that only run an action.
+   */
+  pressable?: boolean
   className?: string
   children: ReactNode
 }
 
 /** Small pill chip: --m-act when active, neutral --m-ic surface otherwise. */
-export default function MChip({ active = false, onClick, size = 'sm', className = '', children }: MChipProps) {
+export default function MChip({ active = false, onClick, size = 'sm', pressable = false, className = '', children }: MChipProps) {
   return (
     <button
       type="button"
       onClick={onClick}
+      aria-pressed={pressable ? active : undefined}
       className={`inline-flex flex-none items-center gap-[6px] rounded-full font-semibold ${
         size === 'tap' ? 'px-[13px] py-[10px] text-[0.8125rem]' : 'px-3 py-[7px] text-[0.75rem]'
       } ${

client/src/mobile/screens/trip/places/MPlacesFilterControls.tsx

@@ -94,7 +94,7 @@ export function MRatingFloorChips() {
   return (
     <div role="group" aria-label={t('places.filterByRating')} className="flex flex-wrap gap-[6px]">
       {RATING_FLOORS.map(floor => (
-        <MChip key={String(floor)} size="tap" active={ratingFilter === floor} onClick={() => setRatingFilter(floor)}>
+        <MChip key={String(floor)} size="tap" pressable active={ratingFilter === floor} onClick={() => setRatingFilter(floor)}>
           {floor === 'all' ? t('common.all') : (
             <>
               <Star size={12} strokeWidth={2.2} fill="currentColor" className="flex-none" />

client/src/mobile/screens/trip/places/MPlacesFilterSheet.tsx

@@ -61,7 +61,7 @@ export default function MPlacesFilterSheet({ open, onClose, places, categories }
           <SectionTitle>{t('places.filterShow')}</SectionTitle>
           <div role="group" aria-label={t('places.filterShow')} className="flex flex-wrap gap-[6px]">
             {pools.map(pool => (
-              <MChip key={pool.id} size="tap" active={filter === pool.id} onClick={() => setFilter(pool.id)}>
+              <MChip key={pool.id} size="tap" pressable active={filter === pool.id} onClick={() => setFilter(pool.id)}>
                 {pool.label}
               </MChip>
             ))}