feat(tokens): allow permanent deletion of revoked tokens

Add POST /admin/tokens/{id}/delete endpoint that permanently removes
a token from the database (only if already revoked). Add delete button
in backoffice UI for revoked tokens.

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

apps/api/src/main.rs

@@ -96,6 +96,7 @@ async fn main() -> anyhow::Result<()> {
         .route("/folders", get(index_jobs::list_folders))
         .route("/admin/tokens", get(tokens::list_tokens).post(tokens::create_token))
         .route("/admin/tokens/:id", delete(tokens::revoke_token))
+        .route("/admin/tokens/:id/delete", axum::routing::post(tokens::delete_token))
         .merge(settings::settings_routes())
         .route_layer(middleware::from_fn_with_state(
             state.clone(),