Fix order-filter dropdowns, restructure Konto identity line, drop blog reset link

- CustomSelect.tsx: mousedown on an option blurred the trigger button
  before the click landed, unmounting the list before anything could be
  selected — add preventDefault on the list's mousedown to stop that.
- KontoShell no longer renders "Eingeloggt als ..." above each page's
  content; each page renders its own title then AccountIdentity right
  below it, and ProfileForm's now-duplicate email/Kundennummer line is
  removed.
- Blog category filter: drop the separate "Zurücksetzen" link — clicking
  an active category badge again already deactivates it.
- Werkzeuge cards: more vertical gap between stacked cards below sm:.
- Legal pages' "Stand: ..." line is now derived from the LegalPages doc's
  own updatedAt instead of a hand-typed string.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_018unaXmuzVA8ct1b6WoyP1U

app/blog/page.tsx

@@ -96,14 +96,6 @@ export default async function BlogOverviewPage({
                     </Link>
                   );
                 })}
-                {activeCategories.length > 0 && (
-                  <Link
-                    href="/blog"
-                    className="inline-flex items-center px-3 py-1.5 text-body-sm font-semibold text-text-muted underline hover:text-brand transition-colors"
-                  >
-                    Zurücksetzen
-                  </Link>
-                )}
               </div>
             )}
           </div>