feat: QR-Code, vCard-Export, Org-Gruppenansicht im Adressbuch

- vcard.ts: shared vCard-Generator (downloadVCard, downloadVCardAll, buildVCardString)
- QrModal.svelte + QrButton.svelte: wiederverwendbare QR-Komponenten mit PNG-Download
- AdressbuchBlock: Org-Gruppenansicht (Toggle), QR + vCard pro Kontakt,
  Buchstaben-Trennzeilen, Such-Highlight, "Alle exportieren", Print-Styles
- ContactCard: vCard-Download-Button
- PostActions: QR-Button für Seiten-URL
- qrcode npm-Paket hinzugefügt

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/lib/vcard.ts

@@ -0,0 +1,47 @@
+import type { ContactEntry } from "./block-types";
+
+function vcardEscape(s: string): string {
+  return s.replace(/\\/g, "\\\\").replace(/,/g, "\\,").replace(/;/g, "\\;").replace(/\n/g, "\\n");
+}
+
+function buildVCard(c: ContactEntry): string {
+  const name = vcardEscape(c.name ?? "");
+  const orgs = (c.organisations ?? [])
+    .filter((o): o is { name?: string } => typeof o === "object" && !!o.name)
+    .map((o) => vcardEscape(o.name ?? ""))
+    .join(", ");
+  return [
+    "BEGIN:VCARD",
+    "VERSION:3.0",
+    `FN:${name}`,
+    "N:;;;;",
+    orgs ? `ORG:${orgs}` : null,
+    c.role ? `TITLE:${vcardEscape(c.role)}` : null,
+    c.phone ? `TEL;TYPE=CELL:${c.phone.replace(/\s/g, "")}` : null,
+    c.email ? `EMAIL:${vcardEscape(c.email)}` : null,
+    c.note ? `ADR:;;${vcardEscape(c.note)};;;;` : null,
+    "END:VCARD",
+  ].filter(Boolean).join("\r\n");
+}
+
+export function buildVCardString(c: ContactEntry): string {
+  return buildVCard(c);
+}
+
+function triggerDownload(content: string, filename: string): void {
+  const blob = new Blob([content], { type: "text/vcard;charset=utf-8" });
+  const url = URL.createObjectURL(blob);
+  const a = document.createElement("a");
+  a.href = url;
+  a.download = filename;
+  a.click();
+  URL.revokeObjectURL(url);
+}
+
+export function downloadVCard(c: ContactEntry): void {
+  triggerDownload(buildVCard(c), `${(c.name ?? "kontakt").toLowerCase().replace(/\s+/g, "-")}.vcf`);
+}
+
+export function downloadVCardAll(contacts: ContactEntry[], filename = "kontakte.vcf"): void {
+  triggerDownload(contacts.map(buildVCard).join("\r\n"), filename);
+}