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/datenschutz/page.tsx

@@ -8,6 +8,7 @@ import { RichText, extractHeadings } from "../components/RichText";
 import { LiveRichText } from "../components/LiveRichText";
 import { SectionTOC, MobileSectionTOC } from "../components/SectionTOC";
 import { getLegalPage } from "../lib/payload";
+import { formatMonthYear } from "../lib/format";
 
 export const metadata: Metadata = {
   title: "Datenschutzerklärung",
@@ -35,7 +36,7 @@ export default async function DatenschutzPage() {
           >
             Datenschutzerklärung
           </p>
-          <p className="text-body text-text-muted">Stand: Juli 2026</p>
+          {page && <p className="text-body text-text-muted">Stand: {formatMonthYear(page.updatedAt)}</p>}
         </Reveal>
 
         {/* MobileSectionTOC — below lg: only, see SectionTOC.tsx's own