feat(search): has:image/file/video filters + recent searches

- Add three msgtype toggle chips (Images/Files/Video) to the search filter
  bar, mirroring the existing "Has link" chip. The Matrix search API can't
  filter by msgtype server-side, so results are post-filtered client-side
  (union match on event.content.msgtype, dropping now-empty groups); the
  server request is unchanged. Visible count may be lower than the server
  total — inherent to client-side filtering.
- Recent searches: last 10 distinct terms persisted via a new
  state/recentSearches.ts (atomWithStorage, error-safe, mirrors
  scheduledMessages). Shown as clickable chips when the search input is
  focused + empty, with a Clear affordance; clicking re-runs the search.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

src/app/features/message-search/useMessageSearch.ts

@@ -26,6 +26,31 @@ export type SearchResult = {
   groups: ResultGroup[];
 };
 
+// Client-side msgtype post-filter. The Matrix search API cannot filter by
+// msgtype server-side, so this is applied to already-returned results.
+export type MsgTypeFilter = 'm.image' | 'm.file' | 'm.video';
+
+/**
+ * Filter result groups to items whose event msgtype is in `msgTypes` (OR/union).
+ * Empty/absent filter returns groups unchanged. Now-empty groups are dropped.
+ */
+export const filterGroupsByMsgType = (
+  groups: ResultGroup[],
+  msgTypes: MsgTypeFilter[],
+): ResultGroup[] => {
+  if (msgTypes.length === 0) return groups;
+  const allowed = new Set<string>(msgTypes);
+  return groups
+    .map((group) => ({
+      ...group,
+      items: group.items.filter((item) => {
+        const msgtype = item.event.content?.msgtype;
+        return typeof msgtype === 'string' && allowed.has(msgtype);
+      }),
+    }))
+    .filter((group) => group.items.length > 0);
+};
+
 const groupSearchResult = (results: ISearchResult[]): ResultGroup[] => {
   const groups: ResultGroup[] = [];