fix(email): import spinnerModule in the modules that use it

Six of the seven modules call `spinnerModule.createWhirlpool(...)` and none
of them imported it. Everything still parsed, every module still loaded, and
the Email Settings page threw `ReferenceError: spinnerModule is not defined`
the moment `settings.js` mounted it — the panel rendered its loading spinner
and stopped there.

The cause is worth writing down because it is the same shape as the bug: the
import statements were collected with a pattern that was not anchored to the
start of a line, and the header comment says "the old import path keeps
resolving". That prose matched first and swallowed the real
`import spinnerModule from '../spinner.js';` that followed it.

`test_no_module_uses_a_package_name_it_never_bound` closes the class. Nothing
else here can: `node --check` parses without resolving scope, and loading a
module does not run the function body where the throw lives. It checks the
package's own vocabulary — every name any module in it binds — rather than
trying to model the browser's globals, so it has no false positives and still
catches the one mistake a split actually makes: the declaration stays behind
and the use moves.

static/js/emailLibrary/reader.js

@@ -9,6 +9,7 @@
 // tab 2 until it closes, even if tab 1 closes first. The slot map here is what
 // holds that.
 
+import spinnerModule from '../spinner.js';
 import * as Modals from '../modalManager.js';
 import { showToast } from '../ui.js?v=20260916largetoolscroll1';
 import { state } from './state.js';