feat(workspace): trash for notes

Deleting a note (or its folder) moves it to the trash instead of erasing
it. Trashed notes leave the tree, search, export and stats and are hidden
from everyone they were shared with; the owner sees them read-only with a
restore banner. New endpoints list, restore, purge and empty the trash;
restoring recreates a deleted folder. Sidebar entry and mobile menu item
with counter, list view with two-tap permanent delete.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

internal/storage/sqlite_test.go

@@ -429,14 +429,16 @@ func TestFolderManagementAndDeletion(t *testing.T) {
 		t.Fatalf("expected 2 deleted docs, got %d (%v)", len(deletedDocs), deletedDocs)
 	}
 
-	// Verify docs are gone from DB
-	_, err = store.GetDocumentByID(user.ID, doc1.ID)
-	if err == nil {
-		t.Fatalf("expected doc1 to be deleted")
+	// The notes are in the trash now, no longer in the tree
+	trash, _ := store.GetTrash(user.ID)
+	if len(trash) != 2 {
+		t.Fatalf("expected doc1 and doc2 in the trash, got %v", trash)
 	}
-	_, err = store.GetDocumentByID(user.ID, doc2.ID)
-	if err == nil {
-		t.Fatalf("expected doc2 to be deleted")
+	docs, _ := store.GetDocuments(user.ID)
+	for _, d := range docs {
+		if d.ID == doc1.ID || d.ID == doc2.ID {
+			t.Fatalf("trashed note %s still in the tree", d.ID)
+		}
 	}
 }