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/useNoteListKeyboard.test.ts

@@ -15,8 +15,6 @@ function makeEntry(path: string, title: string): VaultEntry {
     status: null,
     favorite: false,
     archived: false,
-    trashed: false,
-    trashedAt: null,
     createdAt: null,
     modifiedAt: null,
     fileSize: 100,