fix: exclude trashed notes from search results and autocomplete

Trashed notes were appearing in search (Cmd+F), Quick Open (Ctrl+P),
wikilink autocomplete ([[), and person mention autocomplete (@).

Rust: add is_file_trashed() to check frontmatter, filter search_vault results.
Frontend: filter trashed entries from useNoteSearch, baseItems in both
editor views, and mock search_vault handler.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

src/hooks/useNoteSearch.ts

@@ -32,7 +32,7 @@ export function useNoteSearch(entries: VaultEntry[], query: string, maxResults =
   const typeEntryMap = useMemo(() => buildTypeEntryMap(entries), [entries])
 
   const searchableEntries = useMemo(
-    () => entries.filter((e) => !SEARCH_EXCLUDED_TYPES.has(e.isA ?? '')),
+    () => entries.filter((e) => !e.trashed && !SEARCH_EXCLUDED_TYPES.has(e.isA ?? '')),
     [entries],
   )