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/components/NoteAutocomplete.test.tsx

@@ -15,8 +15,6 @@ const makeEntry = (overrides: Partial<VaultEntry> = {}): VaultEntry => ({
   owner: null,
   cadence: null,
   archived: false,
-  trashed: false,
-  trashedAt: null,
   modifiedAt: 1700000000,
   createdAt: 1700000000,
   fileSize: 100,