refactor(filters): compose the storefront from dimensions and delete the old components (#188)

Replaces App.tsx's hand-written Segmented/Filters-button/ActiveFilterChips
region with a single FilterBar composed from five dimensions, and removes
the FilterDrawer and ActiveFilterChips components along with the
activeFilterCount and hasActiveFilters helpers they were the only callers
of. Catalogue now receives a filtered boolean computed the same way
FilterBar computes its own chip tally, rather than the ItemFilters object
it only ever used for that one check.

frontend/src/filters.ts

@@ -150,13 +150,6 @@ export function filtersFromSearchParams(params: URLSearchParams): ItemFilters {
   };
 }
 
-// One count for the "Filters (N)" button. A price range counts once however
-// many ends are set, since it reads as a single filter to the user.
-//
-// Status is deliberately not counted. It has its own always-visible control
-// beside this button rather than living in the drawer, so counting it would put
-// a number on a button whose drawer shows nothing set — and the control already
-// displays its own position.
 // Named individually rather than grouped, because grouping is what the preset
 // this replaced did. Pending is listed first: "what is waiting to be published"
 // is the question that prompted #132.
@@ -175,24 +168,6 @@ export function statusLabel(status: ItemStatus): string {
   return STATUS_OPTIONS.find((option) => option.value === status)?.label ?? status;
 }
 
-export function activeFilterCount(filters: ItemFilters): number {
-  let count = 0;
-  count += filters.categoryIds.length;
-  count += filters.tagIds.length;
-  if (filters.minPriceCents !== null || filters.maxPriceCents !== null) count++;
-  if (filters.favoritesOnly) count++;
-  return count;
-}
-
-// Broader than the count above, and intentionally so: this decides whether an
-// empty result reads as "no items match these filters" with a way out, or as an
-// empty shop. A status filter that matched nothing is exactly the case where
-// that distinction matters, so it counts here even though it is not in the
-// drawer's tally.
-export function hasActiveFilters(filters: ItemFilters): boolean {
-  return activeFilterCount(filters) > 0 || filters.status !== null;
-}
-
 export interface CategoryNode extends Category {
   children: CategoryNode[];
 }