feat(utils): add fmtLocation to normalize ICS LOCATION strings for display

Strips RFC 5545 backslash-escapes (\n, \,, \;, \\) and collapses
semicolons and newlines into comma-separated inline text.

public/utils/html.js

@@ -25,3 +25,25 @@ export function esc(str) {
   if (str == null) return '';
   return String(str).replace(ESCAPE_RE, (ch) => ESCAPE_MAP[ch]);
 }
+
+/**
+ * Normalisiert einen iCalendar LOCATION-String fuer die Anzeige.
+ * Entfernt ICS-Backslash-Escapes (RFC 5545 §3.3.11) und fasst
+ * mehrzeilige Adressen zu einem einzeiligen String zusammen.
+ *
+ * @param {string|null|undefined} raw
+ * @returns {string}
+ */
+export function fmtLocation(raw) {
+  if (!raw) return '';
+  return raw
+    .replace(/\\[Nn]/g, '\n')   // \n / \N → newline
+    .replace(/\\,/g,  ',')      // \, → ,
+    .replace(/\\;/g,  ';')      // \; → ;
+    .replace(/\\\\/g, '\\')     // \\ → \
+    .replace(/[\n\r;]+/g, ', ') // newlines / semicolons → ", "
+    .replace(/\s*,\s*/g, ', ')  // normalize spaces around commas
+    .replace(/(?:,\s*){2,}/g, ', ') // collapse double commas
+    .replace(/  +/g, ' ')
+    .replace(/^[,\s]+|[,\s]+$/g, ''); // trim leading/trailing commas
+}