fix: CalDAV hrefs with encoded slashes survive the proxy

src/FamilyPlanner.Api/Features/CalDav/CalDavProtocol.cs

@@ -63,7 +63,10 @@ public sealed record DavPath(DavKind Kind, Guid? PrincipalId = null, Guid? Calen
             return new DavPath(DavKind.Unknown);
         }
 
-        string Decode(string segment) => Uri.UnescapeDataString(segment);
+        // YARP kodiert ein bereits kodiertes %2F beim Weiterleiten erneut (%252F). Ein Schrägstrich ist in UIDs möglich (Importe), ein
+        // wörtliches „%2F“ praktisch nie – daher gilt nach dem Dekodieren verbliebenes %2F als Schrägstrich.
+        static string Decode(string segment) =>
+            Uri.UnescapeDataString(segment).Replace("%2F", "/", StringComparison.OrdinalIgnoreCase);
 
         switch (segments.Length)
         {

tests/FamilyPlanner.IntegrationTests/CalDavTests.cs

@@ -57,7 +57,8 @@ public sealed class CalDavTests(AppFixture fixture)
         using var request = new HttpRequestMessage(method, path);
         if (body is not null)
         {
-            request.Content = new StringContent(body, Encoding.UTF8, contentType);
+            request.Content = new StringContent(body, Encoding.UTF8);
+            request.Content.Headers.ContentType = MediaTypeHeaderValue.Parse(contentType);
         }
 
         tweak?.Invoke(request);
@@ -262,7 +263,8 @@ public sealed class CalDavTests(AppFixture fixture)
         foreach (var uid in new[] { "abc123@example.com", "uid mit leerzeichen", "a/b:c" })
         {
             var href = $"{CalendarPath(calendarId)}{Uri.EscapeDataString(uid).Replace("%40", "@")}.ics";
-            Assert.Equal(HttpStatusCode.Created, (await PutAsync(dav, href, Wrap(Vevent(uid, "Sonderzeichen", day)))).Response.StatusCode);
+            var put = await PutAsync(dav, href, Wrap(Vevent(uid, "Sonderzeichen", day)));
+            Assert.True(put.Response.StatusCode == HttpStatusCode.Created, $"{uid}: {(int)put.Response.StatusCode} {put.Body}");
             Assert.Contains($"UID:{uid}", (await SendAsync(dav, HttpMethod.Get, href)).Body);
 
             var listing = await PropFindAsync(dav, CalendarPath(calendarId), 1, "<D:getetag/>");