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/client.yaml

@@ -0,0 +1,22 @@
+services:
+- name: http-proxy
+  addr: :8080
+  handler:
+    type: http
+    chain: quic-chain
+  listener:
+    type: tcp
+
+chains:
+- name: quic-chain
+  hops:
+  - name: hop-0
+    nodes:
+    - name: node-0
+      addr: {{.ServerAddr}}
+      connector:
+        type: http
+      dialer:
+        type: quic
+        metadata:
+          cipherKey: 0123456789abcdef0123456789abcdef

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