refactor: remove Trash system — delete is now permanent with confirm modal

Remove all vestiges of the abandoned Trash system: trashed/trashedAt fields
from types, frontmatter parsing, sidebar filtering, editor banners, inspector
components, mock data, and all related tests. Delete is already permanent via
useDeleteActions with a confirmation dialog. Notes with trashed:true in
existing vault frontmatter are now treated as normal notes (the flag is
ignored by the parser).

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

src/hooks/useNoteSearch.ts

@@ -34,7 +34,7 @@ export function useNoteSearch(entries: VaultEntry[], query: string, maxResults =
   const typeEntryMap = useMemo(() => buildTypeEntryMap(entries), [entries])
 
   const searchableEntries = useMemo(
-    () => entries.filter((e) => !e.trashed && !SEARCH_EXCLUDED_TYPES.has(e.isA ?? '')),
+    () => entries.filter((e) => !SEARCH_EXCLUDED_TYPES.has(e.isA ?? '')),
     [entries],
   )