refactor(css): move email, calendar, notes and task styles to their own file

Second step of splitting static/style.css by panel. This moves the email,
calendar, notes and tasks rules that can move into
static/css/email-calendar-notes-tasks.css.

Same shape as the first step: eager ordered links, verbatim moves, no
rendering change. The header comment in each split file lists the load order
and the earlier file's header is updated so all of them agree.

static/sw.js

@@ -7,7 +7,7 @@
 //   - Other static assets (images/fonts/libs): cache-first with bg refresh.
 //   - API / non-GET: never cached.
 // Bump CACHE_NAME whenever the precache list or SW logic changes.
-const CACHE_NAME = 'odysseus-v652-css-split-1';
+const CACHE_NAME = 'odysseus-v653-css-split-2';
 
 // KaTeX resolves these from its own stylesheet, so caching the CSS without them
 // gives offline math fallback glyphs instead of proper typesetting.
@@ -41,6 +41,7 @@ const PRECACHE = [
   '/',
   '/static/style.css?v=20260921chatgptusage2',
   '/static/css/documents-gallery-editor.css?v=20260923csssplit1',
+  '/static/css/email-calendar-notes-tasks.css?v=20260923csssplit2',
   '/static/app.js?v=20260921chatgptusage2',
   '/static/js/storage.js',
   '/static/js/appConfig.js',