feat: admin settings page UI/UX pass with WordPress-native patterns

- Header: h1 + logo in a wrapping flex row, hr.wp-header-end before the tabs,
  aria-current on the active tab; own CSS/JS enqueued only on this screen.
- Verbindung: ordered "So verbindest du Claude" steps, copy button (core
  clipboard.js + wp.a11y.speak), Site-Health-style status list, German details.
- Zugriff: roles as form-table fieldset, connections with site date format,
  empty-state row, confirm on revoke; ConnectionUsage records last use via
  WP_Application_Passwords::record_application_password_usage (once a day).
- Tools: plain-language legend, counter as inline notice, groups as core
  postboxes (postbox.js toggles, per-user closed state, summary when closed),
  fixed column widths with new "Art" column, submit above and below.
- Protokoll: site-timezone times with UTC tooltip, result icons, filters with
  labels in the list table nav, retention link to Limits.
- Limits: short labels with units and descriptions; snapshot count hidden but
  preserved.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>

tests/Unit/Admin/ConnectionStatusTest.php

@@ -59,8 +59,28 @@ final class ConnectionStatusTest extends TestCase
         $byLabel = array_column($checks, null, 'label');
         self::assertFalse($byLabel['OAuth-Server']['ok']);
         self::assertFalse($byLabel['HTTPS']['ok']);
-        self::assertNull($byLabel['Discovery (/.well-known/)']['ok']);
-        self::assertNull($byLabel['Endpunkt ohne Token']['ok']);
+        self::assertNull($byLabel['OAuth-Discovery']['ok']);
+        self::assertNull($byLabel['MCP-Endpunkt']['ok']);
+    }
+
+    public function testDiscoveryDetailIsGermanInsteadOfTheLibrarysEnglishLabel(): void
+    {
+        Functions\when('get_transient')->alias(static fn (string $key) => $key === 'lit_mcp_endpoint_check'
+            ? false
+            : ['label' => 'MCP OAuth discovery documents', 'status' => 'good']);
+        Functions\when('home_url')->justReturn('https://kunde.test');
+
+        $good = array_column((new ConnectionStatus(static fn (): bool => true))->checks(false), null, 'label');
+        self::assertTrue($good['OAuth-Discovery']['ok']);
+        self::assertSame('Discovery-Dokumente erreichbar', $good['OAuth-Discovery']['message']);
+
+        Functions\when('get_transient')->alias(static fn (string $key) => $key === 'lit_mcp_endpoint_check'
+            ? false
+            : ['label' => 'MCP OAuth discovery documents', 'status' => 'critical']);
+        $bad = array_column((new ConnectionStatus(static fn (): bool => true))->checks(false), null, 'label');
+        self::assertFalse($bad['OAuth-Discovery']['ok']);
+        self::assertStringContainsString('nicht erreichbar', $bad['OAuth-Discovery']['message']);
+        self::assertStringNotContainsString('documents', $bad['OAuth-Discovery']['message']);
     }
 
     public function testPermalinksPrettyReflectsThePermalinkStructureOption(): void