test(e2e): add QUIC cipherKey invalid-datagram regression

Add an e2e suite covering go-gost/x#125: a malformed UDP datagram sent
to a cipherKey-enabled QUIC listener must not close the shared transport.
Uses the canonical http-over-quic chaining pattern and verifies the
forward still works after the invalid datagram.

Also bumps go.mod/go.sum (plugin v0.6.1, otel, x/net, etc.).

tests/e2e/testdata/quic/server.yaml

@@ -0,0 +1,9 @@
+services:
+- name: quic-http
+  addr: :18843
+  handler:
+    type: http
+  listener:
+    type: quic
+    metadata:
+      cipherKey: 0123456789abcdef0123456789abcdef