fix: anchored input patterns end at the last character (/D)

Without /D, "$" also matches before a trailing "\n", so "custom_meta_telefon\n",
a color setting "5\n" (stored as sent) or a whole reference followed by "\n"
passed VariableRef. Added /D to every ^...$ pattern that validates client or
admin input:
- VariableRef META_KEY, NUMBER, WHOLE (canonical/typeOf; Placeholders::field
  shares META_KEY)
- Cursor::decode, GuideRepository topic names (MCP input and filter keys)
- ExposurePolicy::sanitize ability keys and group ids, LogTab list filters

Not changed: Placeholders::PATTERN (runs on trim()), Warnings hex checks (hints
only), NodeSummary/AttrPathIndex/LogListTable (stored or Divi data, no client
input). Each fixed pattern has a test with a trailing "\n" that is rejected.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01At3V6SjwbMe6eMzVGW3Hs7

src/Admin/LogTab.php

@@ -54,7 +54,7 @@ final class LogTab implements AdminTab
         // phpcs:enable WordPress.Security.NonceVerification.Recommended
 
         return [
-            'ability' => preg_match('#^[a-z0-9-]+/[a-z0-9-]+$#', $ability) === 1 ? $ability : '',
+            'ability' => preg_match('#^[a-z0-9-]+/[a-z0-9-]+$#D', $ability) === 1 ? $ability : '',
             'user_id' => $userId,
         ];
     }
@@ -83,7 +83,7 @@ final class LogTab implements AdminTab
 
     private static function isDate(string $value): bool
     {
-        return preg_match('#^\d{4}-\d{2}-\d{2}$#', $value) === 1;
+        return preg_match('#^\d{4}-\d{2}-\d{2}$#D', $value) === 1;
     }
 
     public function render(): void