Match the identity page's tab switcher to the calendar's bigger pill style

Moved into the filter strip, right-aligned like every other page's own
Calendar/List or Week/Month/Season toggle, and switched from the
bespoke .preview-tab/.preview-tab-active classes (now unused, removed)
to the same raw bg-steel pill markup event_list.html already uses.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01ECGMEwrc2k4D8VQuwjstj9

management/tests.py

@@ -4729,7 +4729,7 @@ class ClubSettingsPreviewTests(ManagementTestBase):
     def test_the_page_tabs_and_colour_swatches_render(self):
         response = self.club_get("club_settings")
 
-        self.assertContains(response, "preview-tab-active")
+        self.assertContains(response, "rounded-full bg-steel p-1")
         self.assertContains(response, 'id="primary_color_swatch"')
         self.assertContains(response, 'id="secondary_color_swatch"')