✅ e2e mock: add AppSec scenario + custom remediation header assertion

Address review feedback on the binary e2e suite:

- mocklapi: add an AppSec WAF stand-in (--appsec-addr) that blocks any URI
  containing "rpc2" — the exact probe from examples/appsec-enabled — and allows
  the rest. Lets the suite exercise the plugin's AppSec wiring (header
  forwarding + allow/block enforcement) without the real CRS engine.
- new scenarios/appsec: benign request passes, /foo/rpc2 is 403.
- custom-ban-page: assert the banned response carries the custom remediation
  header (remediationHeadersCustomName), per review.
- README: drop the "don't open issues / AppSec intentionally absent" framing;
  describe what the suite actually covers, including AppSec wiring.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

tests/e2e/mock/scenarios/appsec/dynamic.yml

@@ -0,0 +1,29 @@
+http:
+  routers:
+    r:
+      rule: "PathPrefix(`/foo`)"
+      entryPoints:
+        - web
+      service: backend
+      middlewares:
+        - bouncer
+  services:
+    backend:
+      loadBalancer:
+        servers:
+          - url: "@@BACKEND_URL@@"
+  middlewares:
+    bouncer:
+      plugin:
+        bouncer:
+          enabled: "true"
+          # IP bouncing disabled — this scenario exercises AppSec only.
+          crowdsecMode: none
+          crowdsecLapiScheme: http
+          crowdsecLapiHost: "@@LAPI_HOST@@"
+          crowdsecLapiKey: "@@APIKEY@@"
+          crowdsecAppsecEnabled: "true"
+          crowdsecAppsecScheme: http
+          crowdsecAppsecHost: "@@APPSEC_HOST@@"
+          forwardedHeadersTrustedIps:
+            - "127.0.0.1/32"

tests/e2e/mock/scenarios/appsec/run.sh

@@ -0,0 +1,23 @@
+#!/usr/bin/env bash
+set -euo pipefail
+
+HERE="$(cd "$(dirname "$0")" && pwd)"
+# shellcheck source=../../lib/common.sh
+source "$HERE/../../lib/common.sh"
+
+SCENARIO=appsec
+
+# AppSec wiring check: the plugin forwards each request to the AppSec engine and
+# enforces its verdict. The mock emulates one virtual-patching rule (block any
+# URI containing "rpc2"), mirroring examples/appsec-enabled. This proves the
+# plugin's AppSec path end to end (header forwarding + allow/block handling); it
+# does not test the real WAF's detection accuracy.
+body() {
+  echo "[$SCENARIO] benign request must pass (AppSec allows)"
+  assert_status "http://127.0.0.1:${WEB_PORT}/foo" 200 -H "X-Forwarded-For: 1.2.3.4"
+
+  echo "[$SCENARIO] request whose URI contains 'rpc2' must be blocked (AppSec 403)"
+  assert_status "http://127.0.0.1:${WEB_PORT}/foo/rpc2" 403 -H "X-Forwarded-For: 1.2.3.4"
+}
+
+run_scenario "$SCENARIO" "$HERE" body